The decision to change Russia's official nuclear doctrine is the Kremlin's answer to a reported decision by the administration of U.S. President Joe Biden to allow Ukraine to fire American long-range missiles deep into Russia.

He declared that a conventional attack by any nation supported by a nuclear power will be considered a joint attack on Russia.

President Vladimir Putin approved an update to Russia's nuclear doctrine, widening the scenarios in which it would consider a strike. The move seemed a direct response to events in Ukraine, where the US recently allowed Kyiv to use American weapons for longer-range attacks on Russia.