As the 1973 Yom Kippur war between Israel and neighboring Arab states intensified, I was in an underground missile launch center in Montana with a crewmate when we received an emergency message to prepare for nuclear war with the Soviet Union. Only at the president’s behest would we ever turn keys to fire up to 50 nuclear-armed missiles that could extinguish millions of lives in less than an hour. Once we closed our eight-ton blast door to begin alert duty, we took orders from no one else.

As 20-somethings at the bottom of the nuclear chain of command, launch keys and codes in our anxious hands, we could only imagine how close we were to Armageddon. But we trusted the president to defuse the crisis and avert a nuclear war, and to call upon us to fire only if necessary for the nation’s survival. The whole point would be to never have to fire. Since only he could unleash our weapons of mass destruction — which we could fire in one minute after receiving the order — we felt a trustful, almost intimate connection to the very top of the chain.

We assume that presidents will grasp the power of the nuclear arsenal at their disposal and show the utmost restraint in using it. Dwight D. Eisenhower recoiled at the concept of nuclear overkill, where far more people are killed than necessary to defeat an enemy. After a nuclear war briefing, John F. Kennedy opined in dismay, “And we call ourselves the human race.” Richard M. Nixon (president during the 1973 Arab-Israeli war), in the words of his chief of staff, worried about the way war plans “lightly tossed about millions of deaths.” Ronald Reagan, for all his thunder about the Soviet Union being “an evil empire” and joking that “we begin bombing in five minutes,” was privately averse to nuclear weapons. He wished to eliminate them, as does President Obama.