ISIS is on its heels but fighting to the death

He and other pilots said that the Islamic State fighters were behaving far differently than the Qaeda or Taliban fighters of recent insurgencies. Islamic State fighters, they say, are far slower to abandon entrenched fighting positions. They stay in the territory they have taken until they are, literally, blown out.

In a reflection of that tenacity, some Islamic State fighters in Mosul who refused to surrender were buried under rubble by Iraqi security forces in bulldozers, General Townsend said.

Once American-backed troops move on, the militants often return, no matter how intense the bombing campaign had been. The case of what is known as the Mother of All Bombs illustrates the militants’ determination.