It isn’t pretty, but it’s realpolitik. To Eisenhower, and his successors, the bottom line has been the same: increasing the chance of nuclear conflict is unacceptable when Soviet or Russian misconduct, however shameful or egregious, affects the near periphery of Moscow’s influence and the less urgent bounds of America’s interests. (As Suez demonstrated, it was a lot easier to be tough on allies than on a potentially mortal adversary.)

Thus Lyndon Johnson, as he reported in his memoirs, decided “there was nothing we could do immediately” about the 1968 Soviet invasion of Czechoslovakia—and the non-immediate response would “be no announcements about [Johnson] visiting the Soviet Union or…nuclear talks.” Not long after, Nixon, now president in his own right, reprised the Eisenhower model, opening intense arms control negotiations with the Soviets and making his own historic visit to Moscow.