Defense Secretary James Mattis announced the annihilation strategy in mid-May, but before that, commanders in Iraq and Syria got the go-ahead to fight ISIS, as the Pentagon calls the terrorist army, Trump-style.
Under President Obama, U.S. Army Special Forces assigned to Syrian Democratic Forces needed special approval from Washington for virtually all tactical moves amid the politically complex theater of Americans, Arabs, Kurds, Turks, and Syrians.
In Tabqa, where the city, its dam and its airfield were the objectives, the Green Berets decided they needed an airlift.
Under Mr. Obama, Islamic State terrorists could at times retreat from towns, immune from air strikes if they used civilians as cover.
The battle for Manbij in August became infamous when the SDF let 200 Islamic State fighters turn in their weapons and escape because they had threatened to kill town residents if they were not allowed to run away.
The new Trump strategy calls for surrounding towns, as opposed to pushing from one end or one side to another, in order to isolate Islamic State fighters and annihilate them.