Biden pledges $8 billion to Ukraine following Putin's proposed changes to nuclear rules

President Biden on Thursday pledged another $8 billion in security aid to Ukraine just one day after Russian President Vladimir Putin suggested he might change Moscow’s rules when it comes to its nuclear doctrine. 

In a proposal to the Russian Security Council on Wednesday, the Kremlin chief suggested that any attack by a non-nuclear nation that has the backing of a nuclear-armed nation could be seen as a "joint attack" — a move that could have a resounding impact on the war in Ukraine.