In Kiev, a crowd of some 25,000 people in Independence Square cheered Wednesday as Arseniy Yatsenyuk, 39, was named interim prime minister.

The new cabinet is expected to win easy and quick confirmation Thursday by parliament after mass defection from Yanukovych's ruling Regions Party put the chamber firmly in the opposition's hands.

Several nominations were a clear sign that the protesters were taking charge.

Journalist Tetyana Chornovil -- attacked in December after filing reports about Yanukovych's purported wealth -- was named head of a new anti-corruption committee.

Prominent opposition leader Dmytro Bulatov -- who emerged with a part of an ear missing and caked in blood after being kidnapped in January -- was asked to be Ukraine's ministry of sport and youth.

The vital economy ministry was offered to Kiev School of Economics President Pavlo Sheremeto.

In Moscow, Russian President Vladimir Putin ordered his military to undergo snap combat readiness drills across a western swathe of Russia that also borders the northeast corner of Ukraine.

The drill will include 150,000 servicemen, 90 airplanes, 880 tanks, and up to 80 ships. It started on Wednesday at 2:00pm (1000 GMT) and will last until March 3.

This drew a sharp response from US Secretary of State John Kerry, who warned that any Russian military operations in Ukraine would be a "grave mistake."

Moscow has been venting daily outrage at the dramatic turn of events in a neighbor that Putin views as vital to a post-Soviet alliance.

Diplomatic efforts to defuse tensions will continue, with the EU foreign policy supremo Catherine Ashton announcing she would hold talks with Russian Foreign Minister Sergei Lavrov on March 6 in Rome after she goes to Kiev on Monday.

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