Regarding Afghanistan, some analysts have urged that the United States rely mainly on small numbers of commandos to carry out raids against Al Qaeda and other terrorist groups.

But General McChrystal asserted that such “counterterrorism” operations work best when they are coupled with “counterinsurgency” efforts to build up the ability of the host nation to govern and bolster the capability of its forces.

He also noted that to carry out commando raids, the American military needs bases, an intelligence network and arrangements for medical evacuation. “But if you don’t have the support of the Afghan people, if you are just in there doing what you want to do on their terrain, there’s no reason for them to be supportive of this,” he said. “We’d be fighting our own war on their territory, and they’re just not that interested in that.”

On troop numbers, General McChrystal declined to say how many troops the United States might need to keep in Afghanistan after 2014. (The White House is considering retaining a force of 3,000 to 9,000 troops, which would be complemented by a much smaller number of troops from other NATO nations).

General McChrystal agreed that the American force, currently 66,000 troops, should be substantially reduced. But he cautioned advised against retaining too small a force.