Russia will deploy Tupolev nuclear-capable bomber jets to Crimea in a snap drill, a defence ministry source said Tuesday, as the peninsula marks a year since its annexation by Moscow.

"As part of a snap check of combat readiness of the armed forces, Tupolev 22-M3 strategic missile-carriers will be deployed to Crimea," the source told Russian news agencies, without giving a specific date.

The source said the deployment of the long-range bombers was part of a snap check ordered by President Vladimir Putin on Monday of the combat readiness of more than 40,000 troops nationwide in a major show of strength amid tensions with the West over Ukraine.

Russia said last year it wanted the bombers to be based back in the strategically important Black Sea peninsula, which hosts a major naval base, by 2016. Under the USSR, the bombers were based in Crimea, supporting the navy, but Russia withdrew its planes after Ukraine gained independence.

The European Union warned Monday of the growing militarisation of Crimea as it condemned Moscow's "illegal annexation" of the region from Ukraine.

In a documentary aired Sunday Putin said he was ready to put the country's nuclear forces on alert as he sought to takeover Crimea last year.

The region this week is celebrating the first anniversary since Moscow absorbed it in a move condemned by the West as an illegal takeover but widely backed by Russians.

On Tuesday, the naval city of Sevastopol held events including a flower-laying ceremony at a World War II memorial, with officials releasing doves and holding a minute of silence. Among those attending were bikers from the pro-Putin activist group Night Wolves.

Crimea is holding three days of celebrations culminating Wednesday, which will be a public holiday on the peninsula with patriotic concerts and fireworks.

Pro-Russian authorities said residents voted overwhelmingly to leave Ukraine and join Russia in a hastily-organised referendum on March 16, 2014.

Thousands of unmarked Russian troops had already taken control of the peninsula, although Putin initially denied this. Two days later, Putin signed a deal on Crimea joining Russia.