Ukraine’s Crimea peninsula has voted for full independence from Ukraine in preparation for a referendum to join Russia.

Pro-Kremlin militants on the flashpoint peninsula also seized control of air traffic control at its main international airport and cancelled all flights except for those from Moscow.

The latest escalation of Europe’s worst crisis in decades came moments after ousted pro-Kremlin leader Viktor Yanukovych defiantly vowed to return to Kiev from Russia and declared he was still the leader of the ex-Soviet state.

“As soon as the circumstances allow – and I am sure there is not long to wait – I will without doubt return to Kiev,” Yanukovych told reporters in the southern Russian city of Rostov-on-Don.

Yanukovych still enjoys Moscow’s recognition and remains a political wildcard who the Kremlin says is pushing for Russia’s immediate invasion of Ukraine in the most explosive East-West standoff since the Cold War.

Crimea has been a tinderbox since Russian forces seized control of the rugged peninsula – home to Moscow’s Black Sea Fleet since the 18th century – with help of Kremlin-backed militias days after Yanukovych fled Ukraine last month in response to waves of deadly unrest.

The strategic region’s self-declared rulers are recruiting volunteers to fight Ukrainian soldiers while Russia’s parliament on Tuesday prepared legislation that would simplify the Kremlin’s annexation of Crimea after Sunday’s vote.

But the pro-European leaders in Kiev have rejected the referendum and are appealing to Western powers for both diplomatic backing and pressure on Moscow to release its troops’ stranglehold on the region of two million people.

The North Atlantic Treaty Organization (NATO) responded to the threat of all-out war on Europe’s eastern edge by announcing the planned deployment of AWAC reconnaissance planes in member countries Poland and Romania to monitor any Russian movements.

And French Foreign Minister Laurent Fabius warned that sanctions against Russia could come as early as this week if Moscow failed to respond to Western proposals on the standoff.

Western officials are also expected to meet in London on Tuesday to finalise a list of Russian officials who may face asset freezes and travel restriction over their role in endangering the sovereignty of Europe’s largest state.