Though dominated by hard-core Taliban loyalists, the 25,000 intelligence figure also includes affiliates who are less committed to the fight, officials said. The White House thinks some of them can be split off from the Taliban to weaken the insurgency.

A counterterrorism official said the latest intelligence provided only a rough estimate of the insurgency’s size, citing the difficulty of assessing forces that mainly operate in small units and use hit-and-run tactics.

“You’re not talking about fixed formations that rely solely on full-time combatants. Numbers ebb and flow. Bands of fighters appear and vanish,” the official said.