On the home front: Pakistani demonstrators shout anti-US slogans during a protest against drone strikes earlier this year.
Even as its civilian leaders publicly decried US drone attacks as breaches of sovereignty and international law, Pakistan's top intelligence agency secretly worked for years with the CIA on strikes that killed Pakistani insurgent leaders and scores of suspected lower-level fighters, according to classified US intelligence reports.
Dozens of civilians also reportedly died in the strikes in the semi-autonomous tribal region of Pakistan bordering Afghanistan that is a stronghold of al-Qaeda, Afghan militants, other foreign jihadists and a tangle of violent Pakistani Islamist groups.
Copies of top-secret US intelligence reports reviewed by McClatchy Newspapers provide the first official confirmation of joint operations involving drones between the US spy agency and Pakistan's powerful army-run Inter-Services Intelligence Directorate, or ISI, as well as previously unknown details of that co-operation. The review takes on important significance as the administration reportedly is preparing to expand the use of drones in Afghanistan and North Africa amid a widespread debate over the legality of the strikes in Pakistan.
The documents show that while the ISI helped the CIA target al-Qaeda, the US used drone strikes to aid the Pakistani military in its battle against the Taliban Movement of Pakistan, or TTP, assistance the Obama and Bush administrations never explicitly acknowledged or legally justified.
The White House did not respond immediately to a request for a comment on the McClatchy findings. Pakistan denied there was co-operation.
The partnership was so extensive during the Bush administration that the Pakistani intelligence agency selected its own targets for drone strikes. Until mid-2008, the CIA had to obtain advanced approval before each attack and, under both administrations, Pakistan received briefings and videos of the strikes.
The US intelligence reports illustrate how the Pakistani army retained its grip on national security policy after 2008 elections ended the nation's fourth bout of military rule and brought to power a civilian government, which condemned drone strikes as violations of Pakistan's sovereignty and international law.
What remains unclear is the degree to which the government under President Asif Ali Zardari, which tried unsuccessfully to wrest control of the ISI from the military, acquiesced in the CIA-ISI collaboration.
A spokesman for the Pakistani embassy in Washington said: ''We forcefully contest'' that there was any collaboration between the ISI and CIA on drone strikes.