The central dilemma of the fight against the Islamic State is probably that it can't be won from the air alone, but sending in Western ground forces is almost certainly a losing proposition. One reason is that a ground war against the mighty U.S. military would be a recruitment bonanza for ISIS, at a moment when its volunteer numbers appear to be waning. Another, explains Rukmini Callimachi at The New York Times, is that ISIS "bases its ideology on prophetic texts stating that Islam will be victorious after an apocalyptic battle to be set off once Western armies come to the region."
The stage will be set for the end times, according to ISIS propaganda, when the "Romans" — the U.S. and its allies — enter Dabiq and al-Amaq, two towns that still exist in northern Syria, Callimachi explains, noting that ISIS isn't very subtle on this point: Its monthly magazine is called Dabiq, its new semiofficial news agency is named Amaq, and the group executed American hostage Peter Kassig in Dabiq, saying ISIS is "eagerly waiting for the remainder of your armies to arrive."
“I have said it repeatedly: Because of these prophecies, going in on the ground would be the worst trap to fall into," Jean-Pierre Filiu, a professor of Middle East Studies at France's Sciences Po, tells The New York Times. "They want troops on the ground. Because they have already envisioned it.... It's a very powerful and emotional narrative. It gives the potential recruit and the actual fighters the feeling that not only are they part of the elite, they are also part of the final battle." Read more about ISIS's apocalyptic death wish at The New York Times.