World leaders and security experts have responded to Russian President Vladimir Putin's  decision on Tuesday to suspend the country's participation in a landmark nuclear arms control treaty.

Moscow said on Wednesday it would need to see a change in NATO's stance and a willingness for dialogue before it would consider returning to its last remaining nuclear treaty with the United States.

The potential collapse of the treaty, which limits each country's deployed nuclear warheads to 1,550, has raised the speculation of a new arms race.

Asked in what circumstances Russia would return to the deal, Kremlin spokesman Dmitry Peskov said: "Everything will depend on the position of the West... When there's a willingness to take into account our concerns, then the situation will change."

NATO Secretary-General Jens Stoltenberg urged Russia to reconsider its decision. 

"More nuclear weapons and less arms control makes the world more dangerous," Stoltenberg, standing alongside Ukrainian Foreign Minister Dmytro Kuleba and EU foreign policy chief Josep Borrell, told reporters.

Britain also called on Putin to reconsider his "rash decision." 

"Arms control is vital to the security of our planet," Prime Minister Rishi Sunak's spokesman said.

U.S. Secretary of State Antony Blinken said the move was "deeply unfortunate and irresponsible," 

"We'll be watching carefully to see what Russia actually does. We'll of course make sure that in any event, we are postured appropriately for the security of our own country and that of our allies," he told reporters.

China said the treaty is of vital significance to promoting regional and world peace as well as creating a world without nuclear weapons. 

"China notices the differences between Russia and the U.S.," Foreign Ministry spokesperson Wang Wenbin said. "It hopes the two sides can address these differences through constructive dialogue to ensure the smooth implementation of the treaty."

In a briefing, Stephan Dujarric, spokesperson for the UN secretary-general, said Antonio Guterres' position is clear: "The U.S. and the Russian Federation should resume the full implementation of the new START treaty without delay."

"The new START and successive bilateral treaties on strategic nuclear arms reduction between the two countries have provided security not only for Russia and United States but for the International entire international community," said Dujarric.

Jon B. Wolfsthal, who served as a senior adviser to Barack Obama for arms control and nonproliferation at the national security council, said there's no need for the U.S. to adjust its nuclear posture, because "America still has many more nuclear weapons than it needs to deter Russian nuclear use."

"The U.S. still has extensive ability to monitor Russian nuclear forces even without a treaty in place," he said in a tweet. "But the loss of agreements will increase uncertainty and chances of misunderstanding, inflate threat perception and fuel accelerating arms race."

"While Russia has suspended inspections and consultations, it is not clear whether Russia has or intends to violate any of the treaty's central limitations by deploying additional nuclear weapons," Robert Soofer, a senior fellow in the Scowcroft Center for Strategy and Security's Forward Defense practice, wrote in an analysis published by the Atlantic Council. 

"This seems unlikely, however, because Russia already enjoys a ten-to-one advantage in regional, shorter-range nuclear weapons that are not limited by the treaty," Soofer wrote. 

(With input from agencies)