Biden: Russian nuclear weapon use would be 'serious mistake' warns US President

U.S. President Joe Biden on Tuesday (October 25) said Russia would be making an 'incredibly serious mistake' if it used a tactical nuclear weapon against Ukraine.

"Let me just say, Russia would be making an incredibly serious mistake if it were to use a tactical nuclear weapon," Biden said after getting his updated COVID-19 vaccine. "I'm not guaranteeing you that it's a false flag operation yet, don't know, but it would be a serious, serious mistake."

Russia on Tuesday took its case to the U.N. Security Council that Ukraine is preparing to use a "dirty bomb" on its own territory, an assertion dismissed by Western and Ukrainian officials as misinformation and a pretext for escalating the war.

Moscow sent a letter detailing the allegations to the United Nations on Monday, and Russia raised the issue at a closed meeting with the Security Council.