Biden Putin
Combo pictures created March 17, 2021 shows US President Joe Biden (L) in the White House in Washington, DC on March 15, 2021, and Russian President Vladimir Putin at the Kremlin in Moscow on March 5, 2020. Image Credit: AFP

Washington: US President Joe Biden warned Russia on Tuesday against using a nuclear weapon in the war with Ukraine, saying such an escalation would be a grave error.

Asked by reporters whether he thinks Russia is preparing a dirty bomb attack that it would then blame on Ukraine, Biden said: "Russia would be making an incredibly serious mistake were it to use a tactical nuclear weapon."