Morrell also signaled that the number of troops that McChrystal will ask for - believed to be as high as 40,000 - could change after the report is received if the White House alters its Afghanistan strategy.
“If there are adjustments, there may have to be adjustments made in terms of what’s required of the mission,’’ Morrell said.
He said the Obama administration is taking a new look at how to best achieve its long-stated goal of defeating and dismantling Al Qaeda.
Earlier this year, the Pentagon began ramping up the eight-year war in Afghanistan, targeting extremist Taliban leaders to make sure the nation does not become a safe haven for Al Qaeda.
But White House officials now are looking at sending in air strikes and special operations forces to Pakistan, where Al Qaeda leaders are believed to be hiding.
Morrell said targeting the Taliban in Afghanistan through a counterinsurgency mission “is the strategy and remains the strategy.’’ He added: “There is a discussion taking place about whether it should continue to be the strategy or whether adjustments should be made.’’
Operating under the original strategy would require more combat troops, more trainers for Afghan security forces, more intelligence and surveillance forces, and more helicopters and other support, officials have said in recent weeks.
A senior Republican lawmaker in Congress recently told the Associated Press that McChrystal’s troop request is expected to be as high as 40,000. The lawmaker spoke on condition of anonymity to discuss the issue more freely.
Additionally, two McChrystal advisers, Frederick W. Kagan of the American Enterprise Institute and Kimberly Kagan of the Institute for the Study of War, released a report this week arguing for an additional 40,000 to 45,000 US troops to Afghanistan next year.
Already, Obama has approved increasing the number of US soldiers, sailors, pilots, and Marines in Afghanistan to 68,000 by the end of this year.
Morrell would not discuss the prospects of a new counterterror strategy that White House officials have said could involve expanding missile attacks on Pakistan terrorist havens by unmanned US spy planes.