Putin says that a nuclear power supporting another country's attack on Russia will be considered a participant in aggression.
Speaking during Wednesday's meeting of Russia's Security Council that considered changes in Russia's nuclear doctrine, Putin announced that a revised version of the document says that an attack against Russia by a non-nuclear power with support of a nuclear power will be seen as their "joint attack on the Russian Federation." Putin didn't specify whether Russia could respond to such an attack with nuclear weapons.
The change in the doctrine follows Putin's warning to the U.S.
and other NATO allies that allowing Ukraine to use Western-supplied long-range weapons for strikes on Russia would mean that Russia and NATO are at war.