Former Russian President Dmitry Medvedev urged Japanese Prime Minister Fumio Kishida to disembowel himself after he warned Moscow against the use of nuclear weapons in Ukraine. 

Kishida on Friday met with President Joe Biden, who reiterated his administration's support for Japanese defense efforts, weeks after Tokyo announced its largest military buildup since World War II amid concerns about Chinese military actions. The meeting was seen as strengthening the U.S.-Japan alliance. 

Following the meeting, Biden and Kishida issued a joint statement in which they touched on efforts to see the "denuclearization" of the Korean peninsula. They also spoke against the potential of nuclear weapons being used in the Ukraine war. 

"We state unequivocally that any use of a nuclear weapon by Russia in Ukraine would be an act of hostility against humanity and unjustifiable in any way. And we will continue to support Ukraine in the face of Russia's abhorrent attacks on critical infrastructure," the statement reads.

Their message was met with poor reception from Medvedev, the deputy chairman of Russia's security council.

Once seen as a fairly moderate voice in Russian politics, Medvedev has become a vocal champion of the widely-condemned Ukraine invasion, and has made several controversial remarks since Russian President Vladimir Putin ordered the "special military operation" last February.