Afghan and American officials believe Pakistan's premiere intelligence service, the ISI, maintains influence over the Haqqani network and can help target it or convince it to open a political dialogue.
The three al Qaeda members on the list are as much enemies of Pakistan as they are of the United States.
Ayman al-Zawahiri, who provides much of the ideological base of al Qaeda, regularly urges Pakistanis to rise up against their government and military for supporting U.S. policies.
Ilyas Kashmiri, while slightly lesser known, has emerged as one of the most dangerous terrorists of the past five years, a militant with international goals and connections across the Arab and South Asian worlds. He has been linked with attacks in India and Europe and although the Pakistani army officially denies it, Pakistani military officials admit he received military training. He long ago turned his sights against Pakistan, and Pakistani officials believe he tried to kill then-President Pervez Musharraf in 2003.
Atiya Abdel Rahman is believed to have provided bin Laden a connection with the outside world as the al Qaeda leader hid in Pakistan. A Libyan, he has "been in regular contact with senior ranking al Qaeda leaders" and "has gained considerable stature in al Qaeda as an explosives expert and Islamic scholar," according to the Department of Justice.
Pakistani and U.S. officials believe Rahman might have been killed in a drone strike last fall but say that is unconfirmed.
Today's four hours of meetings in Islamabad were meant to "rebuild the trust" eroded by the U.S.' decision to launch a unilateral raid to kill Osama bin Laden without informing Pakistan beforehand, Mullen said. They were also a sign, in the words of a senior administration official, that the relationship has been "walked back from the brink."
One trust building event occurred this morning, according to Clinton, when the CIA walked into Osama bin Laden's former compound with high tech equipment to find any materials hidden in the walls. The CIA, according to a senior U.S. official, had been asking for access for weeks, and only in the past few days did Pakistanis grant it.
Clinton said bin Laden was a major theme in today's talks, and she said Pakistan officials admitted that "someone, somewhere" helped provide bin Laden support. But she went out of her way to repeat that the U.S. has no evidence senior government officials knew bin Laden was hiding in a large compound just a few thousand feet from Pakistan's equivalent of West Point.
Clinton and Mullen also pushed for help on cracking down on IEDs used in Afghanistan, according to a senior U.S. official. The majority of roadside bombs that have killed more U.S. troops than any other weapon come from materials made in Pakistani factories, according to NATO officials in Kabul, and then are shipped across the border for assembly and placement.
Eight U.S. soldiers died in two IED attacks Thursday in Kandahar only 12 miles from the Pakistani border. It was the deadliest roadside bomb attack since October 2009.
Clinton and Mullen, both of whom looked worried as they walked into the news conference, took pains to acknowledge Pakistani concerns and smooth over the strains in the relationship.
Clinton, especially, acknowledged the sacrifices that Pakistan has made since allying itself with the United States after 9/11.