KABUL, Afghanistan — A multi-day operation in southern Afghanistan this month that involved 200 Special Operations forces and scores of American airstrikes targeted what was “probably the largest” al-Qaeda training camp found in the 14-year Afghan war, the senior U.S. commander in Afghanistan said on Friday.

Army Gen. John F. Campbell, the four-star officer in charge of the U.S. war effort, said the camp was used by AQIS, an acronym for al-Qaeda in the Indian Subcontinent. The group’s formation was announced last year by al-Qaeda leader Ayman al-Zawahiri, and is believed to be based in Pakistan and focused on India, Pakistan and other nations in southern Asia.

The operation, announced by the U.S. military on Oct. 11, hit one training area that sprawled over 30 square miles and another small one that was about one square mile, U.S. military officials said. U.S. and Afghan troops were involved in the ground assault, with 63 airstrikes launched to cover them. Some 160 al-Qaeda fighters were reported killed.

The training camps were found in Kandahar province’s Shorabak district, a sparsely populated area along Afghanistan’s southern border with Pakistan, and the facilities are believed to have been in existence for up to a year.

That in itself has raised questions about the effectiveness of the U.S. military to find and strike the militants 14 years after the Sept. 11, 2001, attacks prompted the United States to topple the Taliban and begin hunting al-Qaeda. U.S. officials have long said that only the bare remnants of al-Qaeda remained in Afghanistan, and that they were concentrated in a few valleys in the eastern part of the country.

“It’s a place where you would probably think you wouldn’t have AQ. I would agree with that,” Campbell said of the Kandahar operation, using an acronym for al-Qaeda. “This was really AQIS, and probably the largest training camp-type facility that we have seen in 14 years of war.”

Campbell, speaking in an interview in his office, said the existence of the camps in Kandahar province were discovered after a raid this summer on another al-Qaeda facility in the Barmal district of eastern Afghanistan’s Paktika province. That rugged, mountainous district borders North Waziristan, in one of Pakistan’s tribal areas with a long history of both al-Qaeda and Taliban operations.

“We looked at it for a while to make sure we reduced the risk to the forces that go in on a target like that,” Campbell said of the operation this month. “It was a very complex target set over several days.”

Campbell said it was initially surprising to find the camps in the south, “but I think as we step back now and really analyze it, it shouldn’t.” The enemy continues to evolve, he said, especially as Pakistan launches operations on its side of the border to root out insurgent fighters and the Islamic State competes with al-Qaeda for global influence.

“What I think you have to do is challenge your assumptions here,” the general said. “Things change, and what was good here in 2010 or 2011 may not necessarily be good today as far as the enemy.”

The training camps were hit just days before President Obama announced Oct. 15 that he will be keeping 9,800 troops in Afghanistan through most of 2016 and 5,500 into 2017, rather than reducing the force to about 1,000 service members by the end of 2016, as he had announced eatlier. He did so after a months-long review and a bloody year in which insurgents have successfully, albeit temporarily, taken control of cities like Kunduz in the north and Musa Qala in Helmand province.

The Islamic State militant group that has terrorized parts of Iraq and Syria also has sprung up in Afghanistan, recruiting in several parts of the country and launching operations in Nangarhar province in the southeast. It also has fought the Taliban, who exert control in the same area.

AQIS began migrating from North Waziristan to southern Afghanistan last year with other al-Qaeda-linked groups after Pakistan launched a military offensive in the region, said Michael Kugelman, a senior associate for South Asia at the Woodrow Wilson Center in Washington. Timing was everything, he added: It would have been helpful to the governments in Kabul and Washington if Pakistan had done so a few years earlier, when the United States had more than 100,000 troops in Afghanistan.

“Instead, you’ve had all these AQIS and other al-Qaeda fighters and their allies flowing into a region of Afghanistan without a foreign combat presence, but with a strong Taliban presence, which in many cases exerts de facto control,” Kugelman said.

Kugelman warned against assuming that all of the militants at the camps targeted were “uniquely AQIS fighters.” Al-Qaeda has a deep bench of militant allies, he said, including fighters who are in the Afghan and Pakistani Taliban.

Campbell did not detail the composition of the ground force involved in the operation in Kandahar province, but credited Afghan Special Operations troops with being involved in a series of raids that produced key intelligence about insurgent groups.

The Afghan government also established this summer an American-style intelligence “fusion cell” that analyzes and compares information collected by Kabul’s defense and interior ministries and its security forces.

Asked about the operation last week, the senior officer in charge of Air Force aviation in Afghanistan, Brig. Gen. David Julazadeh, said that the 455th Expeditionary Air Wing that he commands from Bagram Airfield north of Kabul was “intimately involved” in the planning of the operation in Kandahar province. His wing has F-16 fighter jets at Bagram, along with armed MQ-1 Predator and MQ-9 Reaper drones flying from Jalalabad Airfield and Kandahar Airfield, respectively.

“It was pretty awesome,” Julazadeh said. “I’ll just leave it at that. It was highly coordinated between us and the Special Operations folks.”