MOSCOW — Russia said Thursday it had doubled the number of troops taking part in mass drills ordered by President Vladimir Putin this week to 80,000 in a major show of strength amid tensions with the West over Ukraine.

Putin on Monday ordered drills for more than 40,000 troops in regions spanning the country, from the Arctic to the far east to the volatile southern Caucasus, and ordered nuclear bomber jets to be deployed in Crimea a year after its annexation by Moscow.

Russia's chief of the general staff, Valery Gerasimov, said Thursday that the "number of troops taking part in the exercises has gone up to 80,000, and the number of aircraft has increased to 220," quoted by RIA Novosti state news agency.

Troops in the western and central regions and military aircraft were scrambled for exercises, Gerasimov said.

The drills are the latest in a succession of large-scale military maneuvers that Moscow has ordered as relations with the West have plunged to a post-Cold War low over the crisis in Ukraine.

Ukraine and its Western allies have accused Moscow of pouring thousands of troops over the border to spearhead a pro-Russian uprising aimed at halting Kiev's pivot towards Europe and the United States. Moscow denies the allegations.

Russia said Thursday that thousands of troops had launched war games on the remote Pacific island of Sakhalin close to Japan.

Moscow has deployed "more than 3,000 troops and up to 1,000 units of weaponry and equipment" to Sakhalin, including Osa ground-to-air missile systems and tanks, the defence ministry said.

Russia held triumphant celebrations this week to commemorate a year since it annexed Crimea in a takeover blasted by Kiev and the West as an illegal land grab.

The latest exercises include the deployment of Tupolev nuclear-capable bomber jets to Crimea, where Russia has said it wants to permanently station the long-range bombers in 2016.

In February, Russia launched massive drills involving several thousand soldiers close to its borders with the Baltic states, stoking concerns the Kremlin could try to destabilize the EU member countries after its actions in Ukraine.

The United States then launched a three-month military exercise called Atlantic Resolve in Estonia, Latvia and Lithuania, deploying some 3,000 frontline troops to take part in drills.

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