From The American Conservative, here is an interview with Sibel Edmonds, a former FBI translator who was fired by her former employer under interesting circumstances. I cannot vouch for the credibility of what she says about things she came across while working for the FBI, but in general there is (not just in the U.S. of course) a trade in classified information. In this case, its networks are said to reach from the U.S., through Turkey and Saudi Arabia, to Pakistan (and elsewhere).
This is interesting addition to another recent article, by Greg Miller for the Los Angeles Times, about the GWoT-related links between the CIA and Pakistan's ISI. I earlier cited Azeed Ibrahim's study where reference is made to potentially over $10 billion paid in covert transfers to Pakistan for financing its participation in GWoT-related operations up to 2007. It seemed like a wilder estimate (or one that was possibly valid for covert payments during the entire long-time relationship between the CIA and ISI), and in Miller's article this much is said about this:
"The CIA has funneled hundreds of millions of dollars to Pakistan's intelligence service since the Sept. 11 attacks, accounting for as much as one-third of the foreign spy agency's annual budget, current and former U.S. officials say."
Another interesting figure provided is useful for an assessment of al-Qaida's losses in Pakistan - a former senior CIA official is quoted as saying:
"They gave us 600 to 700 people captured or dead."
To this come added those killed in U.S. drone strikes. Miller's article hints that the above mentioned CIA-ISI liaison was deflated somewhat by AQ operatives leaving cities which were more comfortable hunting ground for the ISI. One wonders now that Karachi is an increasingly important hub for these operatives if this might be changing (again). In any case, the U.S. allegedly isn't paying for information which it uses for its drone strikes.
Meanwhile, that is not all there is to the relationship between the CIA and, as some put it, the ISIs (in plural). This recent article by Seymour Hersh at The New Yorker started much debate also. Assessment is up to you. Interesting ideas raised regarding "bad apples," regarding whether U.S. assistance could or should or has to do anything about those, whether India or the U.S. is liked more in Pakistan etc. A former Pakistan Army officer is quoted as saying "The only good thing the United States did for us was to look the other way about an atomic bomb when it suited the United States to do so" - trust is certainly in short supply on both sides.