Russian troops near the Ukrainian border will return to its permanent bases after completing its military exercises, Russia's Foreign Minister Sergei Lavrov has said, calling for a "de-escalation" of rhetoric.
The killing of protesters in the Ukrainian capital of Kiev took place "under direct leadership" of the country's ex-president Viktor Yanukovich, the head of Ukraine's security service has said.
He added that unidentified Russians were at Ukraine's security service headquarters during the protests.
An unusually frank Nato Secretary General issued an unequivocal warning on the course of events should Russia attack Latvia or Estonia.
The West responds with sanctions and closer political ties with Ukraine as Russia's President seals the annexing of Crimea to much fanfare.
Supporters of the controversial fracking industry believe shale gas could be America's most potent weapon in the stand-off with Russia.