Russia on Monday urged restraint after US President Donald Trump said he had ordered the deployment of two nuclear submarines following an online argument with Russian Security Council Deputy Chairman Dmitry Medvedev.

Speaking to reporters on Monday, Kremlin spokesman Dmitry Peskov said, as reported by The Moscow Times, "We treat any statements on nuclear matters with extreme prudence."

He also said, "Russia is unwaveringly committed to nuclear non-proliferation and believes all parties must exercise maximum restraint with regards to nuclear rhetoric."

Peskov made these remarks after Trump’s announcement about the nuclear submarines and while Trump’s special envoy Steve Witkoff was visiting Moscow.

Talking about Witkoff’s presence in the country, Peskov said, "We are always pleased to see Mr. Witkoff in Moscow. We deem such contact significant, considerable and beneficial," and added that there could be a meeting between Witkoff and President Vladimir Putin.

The dispute between Trump and Medvedev started on Friday after Trump ordered two nuclear submarines to be deployed. This followed a warning by Medvedev, who served as Russia’s President from 2008 to 2012. Medvedev referred to a hypothetical Soviet-era doomsday device that could launch a nuclear counterstrike even if the country’s leadership had been wiped out, according to The Moscow Times.

In a post on X, Medvedev told Trump that every new ultimatum was a "threat and a step towards war." He also warned the United States against playing the "ultimatum game," which appeared to anger Trump.

Later, on Sunday, Trump told reporters that the submarines were "in the region," but he did not disclose their exact location or clarify whether they were nuclear-armed or nuclear-powered.

Responding to Medvedev on Truth Social, Trump wrote, "Based upon the extremely inflammatory remarks of the Former President of Russia, Dmitry Medvedev, the current Deputy Chairman of the Security Council of the Russian Federation, I have directed two Nuclear Submarines to be placed in the relevant areas, just in case these stupid and inflammatory words are more than that."

Peskov dismissed the announcement as part of regular US military activity but commented on the broader suggestion of nuclear confrontation by saying, "there can be no winners in a nuclear war."

This exchange between the two leaders happened even as Trump continued to pressure Russia to end the war in Ukraine. He had initially set a 50-day deadline for a ceasefire but later shortened it to 10 to 12 days due to what he described as his "disappointment" with Putin.