An intelligence official from an Arab nation, who like others spoke on the condition of anonymity to describe evolving assessments, said officials had seen an uptick in jihadist communications about developments in Afghanistan. The Taliban takeover, this official said, “is encouraging many jihadists to think about traveling to Afghanistan now instead of Syria or Iraq.”

According to a European intelligence official, the Taliban’s victory has become a rallying cry for jihadist sympathizers there. “The U.S. appears in all of this now as a weak nation,” he said.

An al-Qaeda fighter who goes by the name Abu Khaled said the Taliban’s conquest was momentous for all extremists. “God willing, the success of the Taliban will be also a chance to unify mujahideen movements like al-Qaeda and Daesh,” he said, using another name for the Islamic State.