Maybe the Apocalypse isn’t upon us after all. The lesson after Iran’s missile strike on U.S. bases in Iraq early Wednesday is that deterrence seems to be working.

More than a dozen ballistic missiles hit two U.S. bases in northern and western Iraq, but no Americans or Iraqis were killed in the attack. Iraq says Iran gave advance warning, so U.S. and Iraqi troops had time to disperse or seek shelter. Iran has made advances in missile targeting, as we learned in the attack on Saudi oil facilities. Yet this time the missiles...