Unmanned CIA aircraft that fly over Pakistan and have enflamed much of the Pakistani population take off and land from at least two heavily guarded airbases inside Pakistan, two Pakistani officials told ABC News. Such flights have drawn repeated government complaints that they violate Pakistani sovereignty.
But the United States has told Pakistan the drones using Pakistani bases are surveillance drones, according to Pakistani intelligence and diplomatic officials, and not the Predator drones that launch missiles into the tribal areas in a campaign targeting al Qaeda leaders.
Privately, though, Pakistani officials doubt that claim, especially after the chairwoman of the Senate Intelligence Committee, Diane Feinstein, D-Calif., suggested 10 days ago that the CIA Predator drones do indeed use Pakistani airfields and not necessarily Afghan airfields, as most assume.
U.S. officials point out that there are many kinds of drones flying above Afghanistan and Pakistan, some for surveillance, some operated by the CIA, and some operated by the U.S. military. There are even some drones being operated by Pakistan, officials said.
The United States has used the CIA attack drones, including at least four times since President Obama's inauguration, as its main tools to attack al Qaeda members in the mostly lawless, hard-to-reach Pakistani tribal areas along the Afghan border.
At least one of those attacks in the past week has targeted the network of Baitullah Mehsud, the chief of the Taliban Movement in Pakistan, a separate Pakistani intelligence official told ABC News.
That could represent a shift in targets to include Taliban militants who tend to attack Pakistani interests and not just al Qaeda militants who tend to attack U.S. interests in the region.
Pakistani officials often privately complain that the drone attacks have focused too much on al Qaeda and not enough on the Taliban. In at least one occasion in the past few years, according to a senior Pakistani military official, the United States has declined to act on Pakistani intelligence with Mehsud's location, saying it was incorrect.
With new technology and a larger network of informants, the drone attacks have become much more accurate in the past six months.
One of the bases being used -- Shamsi -- is a small airstrip located outside Kharan, Baluchistan, near the borders of Afghanistan, Iran and Pakistan, the intelligence official said. During the initial invasion of Afghanistan, Shamsi was used as a staging ground for U.S. forces operating in Afghanistan.
In 2006, the Pakistani government claimed American personnel had left the base. But Google Earth satellite images initially obtained by the Pakistani newspaper The News seem to show three drones parked in the Shamsi airstrip as recently as 2006. A recent Google Earth satellite image shows an air strip with additional buildings created since 2006, but no drones.
Drones are also landing and taking off from the Shahbaz air field, located in Jacobabad, about 300 miles north of Karachi, the intelligence official said. It too was used by American forces after 9/11.
"Under the terms of an agreement with Pakistan, the allied forces can use these bases for search and rescue missions, but are not permitted to use them to stage attacks on Taliban targets," according to GlobalSecurity.org, a public policy group in Alexandria, Va.
According to the Web site of the Defense Energy Support Center, which is an agency in the U.S. Department of Defense, the United States has created contracts to provide both Shamsi and Shabaz with F34 and JP4 jet fuels, respectively. The F34 delivery was first reported by the Times of London. After the story was published, the Web site was scrubbed of any mention of Shamsi.