Prime Minster Stephen Harper is summoning key cabinet ministers to discuss the quickly evolving situation in Ukraine, as the West pleads for restraint and Kiev warns of all-out war now that Russia is postured for an invasion of the crisis-hit former Soviet state.

Russian President Vladimir Putin won his parliament's approval on Saturday to invade Ukraine, where his troops have apparently already seized the strategic Crimea peninsula to the south.

"In response to the very serious developments today, the Prime Minister is convening a meeting of key Cabinet Ministers later this afternoon to discuss the situation in Ukraine," Jason MacDonald, the Prime Minister's spokesman, said Saturday afternoon. "The Prime Minister is following the situation closely and is being briefed regularly by senior officials."

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Mr. MacDonald added the Prime Minister's Office would release a statement following the meeting, though it remains unclear what time the ministers will gather.

Ukraine's newly appointed prime minister, Arseniy Yatseniuk, said Russian military intervention would lead to war and instead called for a political solution.

Mr. Putin's assertion of the right to deploy troops in a country of 46-million people on the ramparts of central Europe creates the biggest confrontation between Russia and the West since the Cold War.

Just a day before Moscow made its intentions publicly known, Foreign Affairs Minister John Baird met in Kiev with the new technical government, and threw Canada's support firmly behind a political transition Mr. Baird said marks a path to European integration. Mr. Harper, too, waded into the fray Friday, pledging Canada's "very strong support" for Ukraine's territorial integrity.

The issue has been at the fore in recent months here in Canada, which is home to more than 1.2 million people who claim Ukrainian heritage ­– the world's third-largest population outside the boundaries of the former Soviet Union.

In January and again earlier this month, Canada imposed travel bans on certain Ukrainian individuals it deemed responsible for human rights abuses during the months-long popular uprising that ousted President Viktor Yanukovych. Ottawa also announced it would freeze assets belonging to certain Ukrainian officials, but those targeted financial sanctions have at least been temporarily suspended now that a new government is at the helm and Mr. Yanukovych has fled to Moscow.

Mr. Harper has been working the phones on this issue, speaking Friday with German Chancellor Angela Merkel, who is considered a main link between Western leaders and Mr. Putin. He spoke earlier this week with British Prime Minister David Cameron, too.

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The crisis in Ukraine erupted in November, when Mr. Yanukovych, a Moscow ally, shunned deeper association with the European Union for closer ties with Russia, which initially offered a $15-billion bailout for the recession-hit nation.

More to come.

With a report from Reuters