Russia has suspended the New START nuclear arms treaty with the United States, Russian President Vladimir Putin said.

But he emphasised that Russia was not leaving the treaty yet, only suspending its participation in its for the time-being.

He blamed the suspension on the West, saying relations had degraded and that it was impossible currently to allow American inspections of Russian strategic nuclear sites.

Putin's decision was announced on Tuesday as he gave an annual state-of-the-union speech in Moscow, days ahead of the one-year anniversary of the invasion into Ukraine.

He also accused the United States of considering restarting nuclear bomb tests and threatened that Russia would hold them too if that happened.

That will be interpreted as a veiled threat in relation to the war in Ukraine -- experts have feared Russia might conduct a nuclear bomb test to intimidate Kyiv and its Western allies. Putin ordered Russia’s military to prepare the possibility to hold a test.

“Some actors in Washington are thinking about testing nuclear weapons,” he said. “The defense ministry and RosAtom must prepare also to conduct nuclear tests in case of necessity. But Russia will not conduct it first.”

-ABC News' Patrick Reevell

Russian President Vladimir Putin on Tuesday opened his state of the union speech in Moscow with familiar touchstones, including ridding the world of Nazism and liberating Ukraine's Donbas region.

He said of his Ukrainian invasion that the "historic events will determine the future of our country ... each of us is bound by a huge responsibility."

And he said he sought an "open dialogue" with the West, but also blamed Western countries and Ukraine's leaders for holding the country's people "hostage."

"The United States and NATO have been rapidly deploying their bases and biolabs at the borders of our country," he said.

He said Russia tried to settle the conflict in the Donbas region by peaceful means, adding that the West's commitment to peace turned out to be "fraud" and a "cruel lie."

Putin said they were open to dialogue with the West and were open to an equal system of security, but "in response we were getting dishonest answers" and specific actions to expand NATO and deploy new anti-missile systems in Europe. He said that "the whole planet is dotted" with U.S. bases.

-ABC News' Joe Simonetti

The Pentagon announced a new presidential drawdown of security aid for Ukraine valued at up to $460 million on Monday.

This package will include four Bradley Infantry Fire Support Team vehicles, HIMARS ammunition, artillery and mortar rounds, air surveillance radars and more.

President Joe Biden hinted at the new supplies in a press conference from Kyiv on Monday, also saying he would be announcing new sanctions "against elites and companies that are trying to evade sanctions and backfill Russia's war machine" later this week.

-ABC News' Matt Seyler

U.S. President Joe Biden said Monday that Russian President Vladimir Putin was "dead wrong" when he started the war in Ukraine on Feb. 24, 2022.

"When Putin launched his invasion nearly one year ago, he thought Ukraine was weak and the West was divided," Biden said in a statement. "He thought he could outlast us. But he was dead wrong."

The White House released the statement from Biden as he made an unannounced visit to the war-torn country, arriving in Kyiv on Monday morning.

"As the world prepares to mark the one-year anniversary of Russia's brutal invasion of Ukraine, I am in Kyiv today to meet with President Zelenskyy and reaffirm our unwavering and unflagging commitment to Ukraine’s democracy, sovereignty, and territorial integrity," Biden said.

"Today, in Kyiv, I am meeting with President Zelenskyy and his team for an extended discussion on our support for Ukraine. I will announce another delivery of critical equipment, including artillery ammunition, anti-armor systems, and air surveillance radars to help protect the Ukrainian people from aerial bombardments," he continued. "And I will share that later this week, we will announce additional sanctions against elites and companies that are trying to evade or backfill Russia's war machine. Over the last year, the United States has built a coalition of nations from the Atlantic to the Pacific to help defend Ukraine with unprecedented military, economic, and humanitarian support -- and that support will endure."

Biden added: "I also look forward to traveling on to Poland to meet President Duda and the leaders of our Eastern Flank Allies, as well as deliver remarks on how the United States will continue to rally the world to support the people of Ukraine and the core values of human rights and dignity in the UN Charter that unite us worldwide."