"The top priority, with respect to that strategy, is to defeat al Qaida, whose leadership resides in the FATA - in the federal areas, the tribal areas - in Western Pakistan," Mullen said in his remarks at a luncheon held at the National Press Club in Washington on Wednesday.

Referring to the recent developments in Pakistan and Afghanistan, Mullen said things are now moving in the right direction and the United States now needs to remain engaged in both the countries.

"A year ago, not many people would have said that the Pakistani military could pull that (Swat) off, and yet they have made an awful lot of progress," he said.

"Then that kind of both effort and the cooperation that we're trying to generate through our engagement in the long run, I think, with the development of the Afghan security forces and the Pakistani security forces, puts growing and continued pressure on that threat that I talked about earlier," Mullen said.