President Vladimir Putin on Tuesday delivered a nuclear warning to the West over Ukraine, suspending a bilateral nuclear arms control treaty, announcing new strategic systems had been put on combat duty and warning that Moscow could resume nuclear tests, reports Reuters.

Speaking nearly a year to the day since ordering an invasion that has triggered the biggest confrontation with the West since the depths of the Cold War, Putin said Russia would achieve its war aims and accused the West of trying to destroy Russia.

Cautioning the United States that it was stoking the war into a global conflict, Putin said that Russia was suspending participation in the New START Treaty, the last major arms control treaty between Moscow and Washington. It limits the number of nuclear warheads the world's two biggest nuclear powers can deploy and is due to expire in 2026.

"I am forced to announce today that Russia is suspending its participation in the Strategic Arms Reduction Treaty," Putin told his country's political and military elite.

The Russian leader said, without citing evidence, that some people in Washington were thinking about resuming nuclear testing. Russia's defence ministry and nuclear corporation should therefore be ready to test Russian nuclear weapons if necessary, he said.

"Of course, we will not do this first. But if the United States conducts tests, then we will. No one should have dangerous illusions that global strategic parity can be destroyed," Putin said.

"A week ago, I signed a decree on putting new ground-based strategic systems on combat duty. Are they going to stick their nose in there too, or what?"

It was not immediately clear which ground-based systems had been put on combat duty.

Russia and the United States still have vast arsenals of nuclear weapons left over from the Cold War. They are by far the biggest nuclear powers, holding between them 90% of the world's nuclear warheads.

The New START Treaty limited both sides to 1,550 warheads on deployed intercontinental ballistic missiles, submarine ballistic missiles and heavy bombers. Both sides met the central limits by 2018.

'IMPOSSIBLE TO DEFEAT'

Speaking for one hour and 45 minutes below a large emblem bearing the two-headed eagle of Russia, and flanked by a total of eight tricolour Russian flags, Putin vowed to continue with Russia's year-long war in Ukraine.

He also sought to justify the war, saying it had been forced on Russia and that he understood the pain of the families of those who had fallen in battle.

The West and would-be NATO member Ukraine reject that narrative, and say NATO expansion eastwards since the end of the Cold War is no justification for what they say is an imperial-style land grab doomed to failure.

"The people of Ukraine have become the hostage of the Kyiv regime and its Western overlords, who have effectively occupied this country in the political, military and economic sense," Putin said.

"They intend to transform a local conflict into a phase of global confrontation. This is exactly how we understand it all and we will react accordingly, because in this case we are talking about the existence of our country."

Defeating Russia, he said, was impossible.

Russia would never yield to Western attempts to divide its society, said the 70-year-old Kremlin chief, adding that a majority of Russians support the war.