(CNN) -- U.S. forces should go into Pakistan to rout al Qaeda from the safe haven it has found in the mountains on the border with Afghanistan, a co-chairman of the Iraq Study Group said.
Former Rep. Lee Hamilton, who also served as the vice chairman of the 9/11 commission, says the Iraq war distracted the United States when it had al Qaeda leader Osama bin Laden on the run in the tribal region between Afghanistan and Pakistan.
He says it's now time to finish the job.
"This has to be carefully calibrated, worked out with the Pakistanis, but I am very concerned that you have a safe haven in Pakistan today where they (al Qaeda) can regroup, rethink, and get ready for more attacks," Hamilton said on CNN's "Newsroom" on Wednesday.
Declassified portions of the National Intelligence Estimate released Tuesday reported that al Qaeda has "protected or regenerated key elements" of its ability to attack the United States while in this region.
Some intelligence analysts believe bin Laden and his second in command, Ayman al-Zawahiri, are hiding in western Pakistan.
"If there's anything we should have learned, it's that we must not let al Qaeda have a sanctuary, which they certainly do in Pakistan today," Hamilton said. Watch Hamilton discuss possible U.S. options »
The United States has accused Pakistan of allowing al Qaeda and the Taliban to have free rein in the region after it pulled out some of its forces in a deal with pro-Taliban tribal chiefs last year.
Under that agreement, the tribal leaders agreed not to harbor any Taliban or al Qaeda terrorists.
Fran Townsend, President Bush's homeland security adviser, said Wednesday "that agreement has failed."
After last week's deadly siege at the Red Mosque in Islamabad that pitted radical Islamists against Pakistan's military government forces, Pakistani President Gen. Pervez Musharraf vowed to "fight against extremism and terrorism no matter what province."
"We will finish it off in every corner of the country," he said.
The United States will keep "working with our Pakistani allies to make sure the tribal area is denied to al Qaeda as a safe haven," Townsend said on CNN's "American Morning."
Hamilton criticized the Pakistani president for keeping U.S. forces out of the region.
"I know Musharraf is described as a great ally of the United States, he's been helpful in some ways, but the fact that he has kept us away from going after these sanctuaries I find unacceptable," the former congressman from Indiana said.
"I think we have to find ways and means, perhaps it's use of covert actions, perhaps it's use of special operations, perhaps it's the pursuit of the Taliban when they're in Afghanistan, to let us go after them as they move back into Pakistan.
"Whatever it is, I do not find acceptable a sanctuary for al Qaeda in Pakistan. We have to be able to go after them." E-mail to a friend