"...maybe the greatest threat that nuclear weapons possess today is that though it may be irrational for any government actually to use them because it could bring about a suicidal effect, if they get into the hands of terrorists, of nonstate actors, they can be used with perhaps impunity. And at the end of the Cold War, we had cooperative agreements with the Russians to secure their nuclear weapons, in what we call the Nunn — Sam Nunn and other senators sponsored this. These have all broken down now... And what worries me is there could be a creeping up of another nuclear arms race, because if the Russian government, if President Putin feels he is being pressed and his security threatened — rightly or wrongly, because it’s perceptions that count — then what’s to keep him, since we have walked out of most of the other agreements, from putting, say, intermediate-range missiles in Kaliningrad or bringing them close to the border? Then what are we going to do? So, to get into another insane arms race, when we have so many other common problems we need to deal with, I think, is extraordinarily unwise."