Ukraine Mobilizes After Putin's 'Declaration Of War' | Natalia Zinets and Alissa de Carbonnel

People watch a Russian Navy ship enter the Crimean port city of Sevastopol March 2, 2014. Credit: Reuters/Baz Ratner

March 3, 2014 -- KIEV/BALACLAVA, Ukraine (Reuters) -- Ukraine mobilized for war on Sunday and Washington threatened to isolate Russia economically, after President Vladimir Putin declared he had the right to invade his neighbor in Moscow's biggest confrontation with the West since the Cold War.

"This is not a threat: this is actually the declaration of war to my country," Ukraine's Prime Minister Arseny Yatseniuk said in English. Yatsenuik heads a pro-Western government that took power when the country's Russia-backed president, Viktor Yanukovich, was ousted last week.

Putin secured permission from his parliament on Saturday to use military force to protect Russian citizens in Ukraine and told U.S. President Barack Obama he had the right to defend Russian interests and nationals, spurning Western pleas not to intervene.

Russian forces have already bloodlessly seized Crimea, an isolated Black Sea peninsula where Moscow has a naval base.

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