President Joe Biden vowed on Tuesday that the US would be steadfast in its support of Ukraine, describing the American commitment to Nato and Ukraine as a battle for freedom against autocracy in a speech delivered hours after a brief but dramatic visit to wartime Kyiv.

Speaking in Warsaw, Biden hailed Ukraine’s defence against Russia’s invasion over the last year, which he called a test of the US, Europe and democracies everywhere.

“Our support for Ukraine will not waver, Nato will not be divided, and we will not tire,” he said. “President Putin’s craven lust for land and power will fail.”

His speech came hours after President Vladimir V. Putin announced Russia would suspend its participation in the New START nuclear arms control treaty, declaring a sharper break with the West by pulling back from the last major such agreement remaining with the US.

In a lengthy national address, Putin again falsely claimed that western nations had “started the war” in Ukraine — an assertion that Biden flatly rejected in Warsaw. “The West was not plotting to attack Russia,” he said, adding a rebuttal of Putin’s arguments that Russia was forced to attack Ukraine.

“This war was never a necessity, it’s a tragedy,” Biden said. “President Putin chose this war. Every day the war continues is his choice.”

The two speeches — three days before the anniversary of Russia’s full-scale invasion — offered a rare moment in which leaders at opposing ends of the global order presented dueling visions of the world nearly side by side. And they come as Russia tries to escalate a new offensive in eastern Ukraine, and while the US and its allies are rushing tanks and armored vehicles to help Kyiv fight back.

Putin’s decision to invade Ukraine has pitted Russia against an American and European alliance that has remained solidly behind Kyiv despite mounting costs and economic turmoil. Ukraine has reclaimed more than half the territory Russia seized since last February, though Russia still controls large swathes of territory in Ukraine’s east and south, and the fighting has killed and wounded hundreds of thousands of people on the two sides and left many cities and towns in ruin.

Before his speech, Biden met Polish President Andrzej Duda as he began a series of consultations with allies to prepare for an even more complicated stage of Russia’s invasion.

“We have to have security in Europe,” Biden said at the presidential palace in Warsaw. “It’s that basic, that simple, that consequential.”

He described Nato as “maybe the most consequential alliance in history”, and he said it’s “stronger than it’s ever been” despite Putin’s hopes that it would fracture over the war in Ukraine.

Earlier on Tuesday, Putin announced that Moscow would suspend its participation in the last remaining nuclear arms control pact with the US.

The so-called New START Treaty caps the number of long-range nuclear warheads they can deploy and limits the use of missiles that can carry atomic weapons.

Biden laid into Putin throughout speech, but did not mention the START suspension. Duda, in his meeting with Biden, praised the American President’s unannounced visit to Kyiv as “spectacular”, saying it “boosted morale of Ukraine’s defenders”. He said the visit was “a sign that the free world, and its biggest leader, the President of the United States, stands by them”. On Wednesday, Biden plans to meet again with Duda along with other leaders of the Bucharest Nine, a group of the easternmost members of Nato military alliance. The conflict in Ukraine has already left thousands of people dead, devastated Ukraine’s infrastructure system and damaged the global economy.

New York Times News Service and AP/PTI