Teller was responding to the assertion that the USA should forego development of a thermonuclear bomb, the “Super” or H-Bomb, because its lethality makes it immoral.

Teller said, in other words, that if something is possible, no one can prevent it’s happening. Or, what can happen will happen.

… the English of which is, “S— happens” … and … it behooves one to be prepared to deal with it before it happens, because it will happen.

Of course, preemption, such as is possible, even if in the end a forlorn effort, would be one reasonable way to deal with s— before it happens.

The people who did this maintain it was moral and so do a lot of residents of New York and other cities: