"I regret today's decision by Russia to suspend its participation in the New START treaty," NATO Secretary General Jens Stoltenberg told a news conference with EU foreign policy head Josep Borrell and Ukraine's Foreign Minister Dmytro Kuleba.

"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," Stoltenberg said.

Borrell said their meeting in Brussels was a historic symbol of the West's unity and determination to protect Kyiv from Russia's aggression.

He agreed about the threat posed by President Vladimir Putin's announcement suspending Russia's participation in the New START treaty.

"Russia's announcement of suspending the New START treaty is another proof that what Russia is doing is just demolishing the security system that was built after the end of the Cold War," Borrell said.

Stoltenberg's warning was stark: "More nuclear weapons and less arms control makes the world more dangerous.

"I'm calling on Russia today to reconsider its decision to suspend its participation in the New START agreement. We have to remember that this is one of the last major arms control agreements we have," he said.