HONG KONG — President Trump and Kim Jong-un, the leader of North Korea, traded threats this week about the size, location and potency of their “nuclear buttons.”

The image of a leader with a finger on a button — a trigger capable of launching a world-ending strike — has for decades symbolized the speed with which a nuclear weapon could be launched, and the unchecked power of the person doing the pushing.

There is only one problem: There is no button. Continue reading.