MOSCOW: President Vladimir Putin on Tuesday delivered a warning to the West over Ukraine by suspending a landmark nuclear arms control treaty, announcing that new strategic systems had been put on combat duty, and threatening to resume nuclear tests.

Alleging that the US was turning the war into a global conflict, Mr Putin said Russia was suspending participation in the New START treaty, its last major arms control treaty with Washington.

The move has evoked condemnation from the EU and Nato with the US calling it “deeply unfortunate and irresponsible”.

The treaty, signed in 2010, caps the number of strategic nuclear warheads that the countries can deploy. Due to expire in 2026, it allows each country to physically check the other’s nuclear arsenal, alth­ough tensions over Ukraine had already brought inspections to a halt.

Russia and the United States together hold 90 per cent of the world’s nuclear warheads. The Treaty limited each side to 1,550 warheads on deployed missile launchers and heavy bombers. Both sides met the central limits by 2018.

The Russian leader said, without citing evidence, that some in Washington were considering breaking a moratorium on nuclear testing.

“A week ago, I signed a decree on putting new ground-based strategic systems on combat duty.” It was not immediately clear which systems he meant.

US Secretary of State Antony Blinken on Tuesday called Russia’s decision to suspend the treaty “deeply unfortunate and irresponsible”, but that the US was willing to talk about the issue.

“We remain ready to talk about strategic arms limitations at any time with Russia, irrespective of anything else going on in the world or in our relationship,” Blinken told reporters at the American embassy in Athens during a regional visit.

Nato’s chief and the EU’s top diplomat have also warned that the suspension of the treaty would mark the end of Europe’s post-Cold War arms control architecture.

“Over the last years, Russia has violated and walked away from key arms control agreements. With today’s decision on New START the whole arms control architecture has been dismantled,” Nato Secretary General Jens Stoltenberg told a news conference with the EU foreign policy head and Ukraine’s foreign mini­ster.