U.S. Defense Secretary Donald Rumsfeld concedes top Taleban and al-Qaida leaders have not yet been found. But Mr. Rumsfeld sounds cautiously optimistic about the prospects of eventually capturing them.

With the Taleban and al-Qaida in retreat, U.S. special forces are now operating in southern Afghanistan, hunting for the group's leaders - including Mullah Mohamed Omar and Osama bin Laden.

Defense Secretary Rumsfeld confirms that finding them is now the top U.S. priority. But speaking to reporters during a visit to New York City where he toured the World Trade Center ruins, he says it is not an easy job. "Our task is to find the Taleban and al-Qaida leadership. We still have that ahead of us. So we have to be purposeful about that and recognize that's going to continue to be a difficult task. Finding handfuls of people is indeed like finding needles in a haystack and it's a complicated process," he said.

Still, Mr. Rumsfeld sounds a cautiously optimistic note about the prospects of eventually tracking down Taleban and al-Qaida leaders. "But because of all the pressure that's been put on across the globe, the drying up of bank accounts, the numbers of arrests that have been made, the interrogations that have been held, the intelligence that has been gathered, I think that every day we have a better chance of achieving our goal," he said.

Mr. Rumsfeld says U.S. special forces are closely monitoring the main roads connecting northern Afghanistan with the southern part of the country in an effort to intercept Taleban and al-Qaida leaders.