An anti-Yanukovych protester sets an European Union flag on top of a tent in Kiev's Independence Square, the epicenter of the country's current unrest, Ukraine, Sunday, March 2, 2014. A convoy of hundreds of Russian troops is heading toward the regional capital, Simferopol on the Crimean peninsula in Ukraine today. On the road from Sevastopol, the Crimean port where Russia maintains a naval base, AP journalists saw 12 military trucks. Russian troops took over the strategic Black Sea peninsula yesterday and are ignoring international protests. (AP Photo/Emilio Morenatti)

Demonstrators shout slogans during a rally in Kiev's Independence Square, the epicenter of the country's current unrest, Ukraine, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Emilio Morenatti)

People gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Emilio Morenatti)

People applaud as the European Union flag held by a protester arrives at the Independence square during a rally in Kiev Ukraine, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Emilio Morenatti)

People gather during a rally in Kiev's Independence Square, the epicenter of the country's current unrest, Ukraine, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Emilio Morenatti)

People gathering in a rally are seen through a poster with photos of people killed during recent clashes in Kiev's Independence Square, Ukraine, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Emilio Morenatti)

People hold photos of their relatives killed during recent clashes, during a rally in Kiev's Independence Square, Ukraine, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Emilio Morenatti)

Protesters holding flags from USA, Germany and Italy, arrive at Independence Square during a rally in Kiev Ukraine, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Emilio Morenatti), APTOPIX

Foreign citizens rally to support Ukraine's territorial integrity in front of the parliament in Kiev, Ukraine, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Andrew Kravchenko)

Foreign citizens rally to support Ukraine's territorial integrity in front of the parliament in Kiev, Ukraine, Sunday, March 2, 2014. A poster reads :" Ukraine, we love you!" Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Andrew Kravchenko)

A woman reacts, during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Sergei Chuzavkov)

People gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Sergei Chuzavkov), APTOPIX

People gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Sergei Chuzavkov)

People gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot.(AP Photo/Sergei Chuzavkov)

People shout slogans during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Sergei Chuzavkov)

People gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot.(AP Photo/Sergei Chuzavkov)

Nadia Lysenko from Kiev takes part in a Ukrainian demonstration outside the Russian Embassy in London, Sunday, March, 2, 2014. British Foreign Secretary William Hague says he is traveling to Kiev because he wants to meet personally with Ukraine's new leaders to discuss ways to defuse the crisis. Hague said Ukrainian officials have told him via telephone that they will not respond to Russian provocations and he advised them to "continue with that course." Hague says Britain will pull out of planned preparatory talks for the upcoming G-8 summit in Russia in protest.(AP Photo/Alastair Grant)

Ukrainian demonstrators take part in a protest outside the Russian Embassy in London, Sunday, March, 2, 2014. British Foreign Secretary William Hague says he is traveling to Kiev because he wants to meet personally with Ukraine's new leaders to discuss ways to defuse the crisis. Hague said Ukrainian officials have told him via telephone that they will not respond to Russian provocations and he advised them to "continue with that course." Hague says Britain will pull out of planned preparatory talks for the upcoming G-8 summit in Russia in protest.(AP Photo/Alastair Grant)

People gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot.(AP Photo/Sergei Chuzavkov), APTOPIX

People shout slogans and gesture, during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Sergei Chuzavkov)

People gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot. (AP Photo/Sergei Chuzavkov)

A poster with the caricature of Russian President Vladimir Putin, on display as people gather during a rally in Kiev's Independence Square, Sunday, March 2, 2014. Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military Sunday in the conflict between the two countries, warning that "we are on the brink of disaster." The comments from Arseniy Yatsenyuk came as a convoy of Russian troops rolled toward Simferopol, the capital of Ukraine's Crimea region, a day after Russian forces took over the strategic Black Sea peninsula without firing a shot.(AP Photo/Sergei Chuzavkov)

A woman lights a candle at a memorial for the people killed in recent clashes with the police at Kiev's Independence Square, Ukraine, Sunday, March 2, 2014. Russia's parliament approved a motion to use the country's military in Ukraine after a request from President Vladimir Putin as protests in Russian-speaking cities turned violent Saturday, sparking fears of a wide-scale invasion. (AP Photo/Emilio Morenatti)

People gather during a rally in Kiev's Independence Square, the epicenter of the country's current unrest, Ukraine, Sunday, March 2, 2014. As hundreds of armed men surrounded a Ukrainian military base in Crimea on Sunday, world leaders and Ukraine's new prime minister urged Russian President Vladimir Putin to pull back his military.(AP Photo/Emilio Morenatti)

A so-called Maidan self defence unit member stands at the Independence square in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

An elderly couple warms by a stove at the Independence square in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

A woman takes pictures of an artwork featuring former Ukrainian President Viktor Yanukovych and the Russian President Vladimir Putin in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

A so-called Maidan self defence unit's member guards outside the parliament in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

An unit guards outside the parliament in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

A woman tries the food she prepares at a barricade in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

Pigeons fly while people attend a rally against Russia on Kiev's Independence square on March 2, 2014. Pro-Russian forces tightened their grip on Crimea on Saturday as the Kremlin vowed to help restore calm on the restive Ukrainian peninsula and Washington warned of "costs" to Moscow should it order in troops. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

A woman holds a placard displaying a caricature of Russian President Vladimir Putin during a rally against Russia on Kiev's Independence square on March 2, 2014. Pro-Russian forces tightened their grip on Crimea on Saturday as the Kremlin vowed to help restore calm on the restive Ukrainian peninsula and Washington warned of "costs" to Moscow should it order in troops. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

TOPSHOTS A so-called Maidan self defence unit member guards at the Independence square in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

TOPSHOTS A so-called Maidan self defence unit member stands at the Independence square in central Kiev on March 2, 2014. Ukraine accused Russia of sending thousands of extra troops into Crimea as the Kremlin vowed to help restore calm on the flashpoint peninsula and Washington warned of "costs" to Moscow should it use force. AFP PHOTO / LOUISA GOULIAMAKI

People hold up different national flags as they attend a rally against Russian intervention on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally on Kiev's Independence square on March 2, 2014, against Russian intervention. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO / BULENT KILIC

A demonstrator dressed as the Grim Reaper, the personification of death, holds up a scythe reading "Putin, I am behind you", during a rally against Russian intervention on Kiev's Independence square on March 2, 2014. Ukraine said on March 2 that it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO / BULENT KILIC

People attend a rally against Russian intervention in Ukraine on Kiev's Independence square on March 2, 2014. Ukraine said on March 2 that it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO / LOUISA GOULIAMAKI

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO / LOUISA GOULIAMAKI

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

People hold a placard reading "Putin-Hitler XXI century" during a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

People attend a protest at Russia's stance in the Ukraine crisis on Independence square in Kiev on March 2, 2014. Tensions have simmered in Crimea since Ukraine's Russian-leaning president Viktor Yanukovych was ousted a week ago, with calls for the autonomous republic to secede from the rest of the country. AFP PHOTO / LOUISA GOULIAMAKI

A man attends a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

People attend a protest at Russia's stance in the Ukraine crisis on Independence square in Kiev on March 2, 2014. Tensions have simmered in Crimea since Ukraine's Russian-leaning president Viktor Yanukovych was ousted a week ago, with calls for the autonomous republic to secede from the rest of the country. AFP PHOTO / LOUISA GOULIAMAKI

A woman holds a placard reading "Crimea is Ukraine" while people attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

People, waving a flag of the European Union with the inscription "You like Ukraine!" attend a rally to protest Russia's stance in the Ukraine crisis, on Kiev's Independence square on March 2, 2014. Ukraine is to call up all military reservists, the head of the national security and defence council said on March 2, 2014, after Russia's parliament approved the deployment of troops in the country. AFP PHOTO / LOUISA GOULIAMAKI

People, one holding a photo of Russian President Vladirmir Putin caricatured as Adolf Hitler, attend a rally to protest Russia's stance in the Ukraine crisis, on Kiev's Independence square on March 2, 2014. Ukraine is to call up all military reservists, the head of the national security and defence council said on March 2, 2014, after Russia's parliament approved the deployment of troops in the country. AFP PHOTO / LOUISA GOULIAMAKI

People attend a rally to protest Russia's stance in the Ukraine crisis, on Kiev's Independence square on March 2, 2014. Ukraine is to call up all military reservists, the head of the national security and defence council said on March 2, 2014, after Russia's parliament approved the deployment of troops in the country. AFP PHOTO / LOUISA GOULIAMAKI

People holding photos of some of the ones who were killed during recent clashes on Independence square, attend a protest at Russia's stance in the Ukraine crisis on Independence square in Kiev on March 2, 2014. Tensions have simmered in Crimea since Ukraine's Russian-leaning president Viktor Yanukovych was ousted a week ago, with calls for the autonomous republic to secede from the rest of the country. AFP PHOTO / LOUISA GOULIAMAKI

French public intellectual and author Bernard-Henri Levy speaks during a rally at Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

People gather for a rally against Russian intervention in Ukraine on central Kiev's Independence square on March 2, 2014. Ukraine said on March 2 that it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO / LOUISA GOULIAMAKI

A demonstrator wearing a picture of Russian President Vladimir Putin caricatured as Adolf Hitler and dressed as the Grim Reaper, the personification of death, holds up a scythe reading (top) "PR and CPU I am waiting for you" (referring to the Party of Regions and the Communist Party of Ukraine) and "Yanukovych you are mine" (along the handle) gestures during a rally against Russian intervention in Ukraine on central Kiev's Independence square on March 2, 2014. Ukraine said on March 2 that it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO / LOUISA GOULIAMAKI

A woman holds a sign reading "Putin fuck off!" as she stands with her family in front of the Ukrainian parliament, in Kiev, on March 2, 2014. Ukraine warned on March 2, 2014 that it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/ ANATOLII STEPANOV

TOPSHOTS People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

TOPSHOTS People attend a rally against Russia on Kiev's Independence square on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO/BULENT KILIC

Young women hold signs as they take part in a protest against war and Russian interference in Ukrainian political affairs at Kiev's Independence square, on March 2, 2014. Ukraine said today it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula. AFP PHOTO / LOUISA GOULIAMAKI

A woman photographs Kiev's Independence square as protests continue on March 2, 2014. Ukraine said Sunday it would call up all military reservists after President Vladimir Putin's threat to invade Russia's neighbour drew a blunt response from US President Barack Obama. The stark escalation in what threatens to become the worst crisis in relations since the Cold War came as pro-Russian forces seized control of key government buildings and airports in the strategic Crimean peninsula.AFP PHOTO / LOUISA GOULIAMAKI

Men hold a banner with a European flag and text reading "We love Ukrainians !" as foreigners living in Ukraine carry their national flags and take part in a demonstration entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

Men hold a banner with a European flag and text reading "We love Ukrainians !" as foreigners living in Ukraine carry their national flags and take part in a protest march entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

Men hold a banner with a European flag and text reading "We love Ukrainians !" as foreigners living in Ukraine carry their national flags and take part in a demonstration entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

Foreigners living in Ukraine carry their national flags during mass rally in Kiev called "Ukraine and Crimea are together" on March 2, 2014. AFP PHOTO/ YURIY DYACHYSHYN

A man holds a sign depicting Russian President Vladimir Putin as World War II German dictator Adolf Hitler with text reading "Putler you're finished !" during a demonstration entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

A view of Kiev's Independence square seen through a European flag, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

Head of the Ukrainian UDAR (Punch ) party Vitali Klitschko greets people during a demonstration entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

Foreigners living in Ukraine carry signs and their national flags as they take part in a demonstration entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

Head of the Ukrainian UDAR (Punch ) party Vitali Klitschko greets people during a demonstration entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN

A woman holds a sign depicting Russian President Vladimir Putin as the devil with text reading "You will have to kill all of us, not choke us with our blood" during a demonstration entitled "Ukraine and Crimea are together" in Kiev, on March 2, 2014. Ukraine warned today it was on the brink of disaster and called up all military reservists after Russia's threat to invade its neighbour drew sharp rebukes from the United States and its Western allies. AFP PHOTO / YURIY DYACHYSHYN