President Vladimir Putin rattled Russian sabres and Western nerves Wednesday, putting troops on high alert and ordering war games near Ukraine's border even as U.S. and European leaders sought to defuse tensions.
President Barack Obama quickly responded with a warning that "outside actors" should "end provocative rhetoric and actions" and "use their influence in support of unity, peace and an inclusive path forward," according to a statement from White House spokesman Josh Earnest aboard Air Force One as the blue-and-white Boeing 747 headed for Minnesota.
And the United States chided Russia by reminding it of "commitments to transparency about military activities" under international obligations designed to ensure peace and security in the Euro-Atlantic region.
Meanwhile, ethnic Russians in the strategic but volatile Crimean peninsula clashed with tens of thousands of Muslim Tatars, who fear any return to Moscow's rule.
In Brussels, North Atlantic Treaty Organization defence ministers ignored Russia's war games and called for calm and co-operation in Ukraine's unfolding crisis. The Western alliance, including Canada, said it supported "Ukrainian sovereignty and independence, territorial integrity, democratic development, and the principle of inviolability of frontiers."
U.S. Secretary of State John Kerry tried to head off a Moscow-Washington clash over Ukraine's future. "It is not a West versus East," he said. "It is not Russia or the United States. This is about the people of Ukraine and Ukrainians making their choices about the future and we want to work with Russia and other countries, with everybody available, to make sure this is peaceful from this day forward."
But at least for some factions inside Ukraine, the stark choice facing the violence-torn, economically ravaged and strategically located nation of 46 million people is between a closer alliance with western Europe and a return to the Russian fold.
In the Crimea, handed to Ukraine by the former Soviet leader Nikita Khrushchev 60 years ago, ethnic Russians clashed Wednesday with crowds backing the new, transitional government in Kiev.
Moscow has accused the West of backing the huge protests that toppled pro-Russian president Viktor Yanukovych, now a fugitive wanted for mass murder and believed to be hiding somewhere in Crimea.
The huge demonstration by mostly Muslim Tatars in Crimea was to counter a rise in secessionist fervour among Russians.
Russia still maintains a major naval base – its second largest – in the Crimean port of Sevastopol.
Russian Defence Minister Sergei Shoigu said the previously unannounced military exercises close to the Ukrainian border were intended to check military readiness.
NATO Secretary-General Anders Fogh Rasmussen avoided an escalation in rhetoric in response to the Russian military moves. "We are encouraged that violence [in Ukraine] has been stopped through negotiations. As Ukraine goes forward, an inclusive political dialogue, which respects democratic values, is key," he said.
NATO has invited Ukraine to join the military alliance – a move bitterly opposed by Russia. Mr. Shoigu said Moscow was "carefully watching what is happening in Crimea" and would take "measures to guarantee the safety of facilities, infrastructure and arsenals of the Black Sea fleet."
With reports from Reuters and The Associated Press.