I think there is easily a greater than 5% chance of Russia using nukes in the case of an all out war between Russia and Ukraine.  (Remember how realistic it was for the US to develop small bunker-buster weapons just a few years ago?  What sorts of tactical nukes do you think Russia has stored away somewhere?)  Any that&#x27;s plenty of risk to dramatically influence the conflict, whether diplomatic or violent.<p>So now you&#x27;re talking about a case where the US is violating both the spirit (no UN petition) and the letter (no meaningful aid) of the memorandum, although doing each in different ways.    At that point, I think the damage is done.  Other countries will not and should not expect the US to honor agreements it makes, even on the deathly serious issue of voluntarily giving up nuclear weapons.