As the debate on how best to contain the Islamic State continues to rage in Western capitals, the militants themselves have made one point patently clear: They want the United States and its allies to be dragged into a ground war.

In fact, when the United States first invaded Iraq, one of the most enthusiastic proponents of the move was the man who founded the terrorist cell that would one day become the Islamic State, Abu Musab al-Zarqawi. He excitedly called the Americans’ 2003 intervention “the Blessed Invasion.”

His reaction — ignored by some, and dismissed as rhetoric by others — points to one of the core beliefs motivating the terrorist group now holding large stretches of Iraq and Syria: The group 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.

Should that invasion happen, the Islamic State not only would be able to declare its prophecy fulfilled, but could also turn the occurrence into a new recruiting drive at the very moment the terrorist group appears to be losing volunteers.