double tap

In the 1930s two British police chiefs, William Ewart Fairbairn and Eric A. Sykes, developed a technique for firing a gun which gave better penetration with the kind of bullets they were using. The idea was that the shooter would take aim, fire the gun, and then immediately take aim again, and fire again. This all happened so fast that it looked as if the shooter was simply firing twice.  This was called the double tap and became routine in  firearms training.

Now that term has been employed to refer to the practice of following up any sort of military attack, whether it be a missile or an IED or an airstrike, with a second one shortly afterwards which often hits all those who have rushed to the aid of the first victims.