Lawmakers in Ukraine's Crimea region voted Thursday in favor of leaving Ukraine for Russia, which already has the Black Sea peninsula under de facto control, and set a referendum on the move for 10 days' time.
Citizens of Crimea will face a simple choice: Stay in Ukraine or join Russia.
It's not clear how easily the region could split off if the referendum endorses the move.
The autonomous region has a 60% ethnic Russian population, having been part of Russia until it was ceded to Ukraine in 1954 by the Soviet Union.
But not everyone may be as keen on coming under Moscow's direct influence. A quarter of the peninsula's population is Ukrainian and about 12% Crimean Tatars, a predominantly Muslim group.
The parliament in Crimea installed a new, pro-Moscow government late last month. It had previously said a referendum would be held at the end of March on greater autonomy for Crimea.
Citizens will now be asked on March 16 if they want an autonomous republic of Crimea within Russia; or within Ukraine.
Michael Crawford, a former long-serving British ambassador in Eastern Europe, cautioned that whatever the result, it may be meaningless.
"It does not follow that if Crimea votes to join Russia, that anyone will accept it," he said.
"For Russia to start cherry-picking bits of the former Soviet Union, cranking up referenda in Kazakhstan or Latvia or wherever you like, to try to carve off bits, would be against international law, and it would be something Vladimir Putin has said he doesn't want to do."
Putin, the Russian President, has insisted Russia has the right to use military force in Ukraine if necessary to protect ethnic Russians.
But he has denied claims by Ukrainian officials and Western diplomats that Russia has sent thousands of troops into the region in recent days. Russia says the heavily armed troops, in uniforms without insignia, are local "self-defense" forces.
The deputy speaker of the Crimean parliament, Rustam Temirgaliev, said Thursday at a news conference that the only forces allowed in Crimea are the Russian military - and that all others will be considered to be occupying forces.
He said he'd advised Ukrainian troops to swear allegiance to the Russian army or leave Crimea under safe passage.
In the regional capital, Simferopol, residents have demonstrated this week against the interim government in Kiev, with crowds chanting in favor of Putin.
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