In response to a question about what the worst US foreign policy disaster has been, Mearsheimer agreed with a fellow panelist that at that moment Iraq looked like the worst, but said he believed US policy on Ukraine would prove much worse in coming years. He spoke of the fact that Russia has thousands of nuclear weapons, and that it's entirely possible those weapons will be used if Russia feels threatened.

"Because the Cold War is in the distant past, most people, especially younger people, haven't thought a lot about nuclear weapons and nuclear deterrence, and they tend to be quite cavalier in their comments about nuclear weapons, and this makes me very nervous," Mearsheimer said.