Senior U.S. military commanders are now openly complaining about Pakistani intelligence officials passing on information revealing American and NATO operations against al Qaeda and the Taliban. For several years now, the United States, Afghanistan, India and many Pakistanis, have been quietly pressuring the Pakistani government to reform the ISI (Inter Service Intelligence agency). This organization has long been a power unto itself, with its own agenda and many members who support Islamic radicalism. It's ISI that is responsible for most of the leaks.
Last year, the government disbanded the political wing of the ISI. This section was believed be largely responsible for Pakistani support of Islamic, or simply Pakistani, terrorist operations in Afghanistan and India, as well as support for Taliban and al Qaeda in Pakistan itself. The political wing has also served as a domestic spying operation whenever the military was running the country (which is more than half the time.) Pakistan is currently run by a civilian government that came into power last Summer. Unfortunately, no one was fired or dismissed when the Political Wing was eliminated. The officers and staff were simply transferred to other jobs within ISI.
ISI has long supported Islamic terrorists. This time, Pakistan appears determined to root out "Taliban spies" in the ISI. No one is optimistic about how successful this attempt will be. The problem is that these Islamic radicals have been operating openly in the ISI for three decades, and were put there by the government in the late 1970s, when it was decided that Islamic conservatism was the solution for Pakistan's problems (corruption and religious/ethnic conflicts.) These guys are not just "Taliban spies," but Pakistani intelligence professionals that believe in Islamic radicalism.
The ISI itself was created in 1948 as a reaction to the inability of the IB (Intelligence Bureau, which collected intelligence on foreign countries in general) and MI (Military Intelligence, which collected intel on military matters) to work together and provide useful information. The ISI was supposed to take intel from IB and MI, analyze it and present it to senior government officials. But in the 1950s, the government began to use the ISI to collect intel on Pakistanis, especially those suspected of opposing whatever government was in power. This backfired eventually, and in the 1970s, the ISI was much reduced by a civilian government. But when another coup took place in 1977, and the new military government decided that religion was the cure for what ailed the country. This proved to be a terrible mistake, and lots of Islamic radicals holding down key ISI jobs is but one of many aftereffects.