Vladimir Putin and the leaders of Crimea signed a bill to formally absorb the peninsula into Russia.
In an anger-tinged speech, the Russian president claimed the West was supporting a new “extremist” right-wing government in Ukraine, despite the pro-EU administration being widely seen as moderate.
The development came as the United States confirmed it is considering sending troops for war games in the Baltic states bordering Russia. Vice president Joe Biden said the move would be to reassure Nato allies in Europe alarmed at the Kremlin’s intervention in Ukraine.
Moscow’s despatch of troops to Crimea and its unilateral declaration the area is now part of Russia that have left Nato member states in eastern Europe worried they could be next in line.