A senior Defense Department official said he understood the frustration of intelligence operatives, planners and “the guys ready to go.”

But this “was a risky operation, deep into Syria, where we hadn’t been before,” he said. “It involved a lot of people,” with substantial danger to both the troops and the hostages themselves. “It wasn’t a nice little surgical operation.”

Moreover, while the rescuers found evidence at the site that the hostages had been there, the mission was launched with no definitive intelligence confirming their presence.

“There wasn’t a hot, smoking trail,” the Pentagon official said.