ISLAMABAD (Reuters) -- A pilotless U.S drone aircraft has crashed in the northwestern Pakistani region of South Waziristan but it was not clear why it came down, Pakistani news channels reported.
U.S. forces have launched a string of attacks with missiles fired by drones, and one ground assault, on militant targets in northwestern Pakistan in recent weeks, infuriating the U.S. ally, which says the attacks are a violation of Pakistani sovereignty.
The drone reportedly came down near the border village of Angor Adda, where U.S. commandos launched a ground assault on September 3 that Pakistani officials said killed 20 people, including women and children.
A Pakistani intelligence official in the region said he had no information but he had heard claims from a Taliban faction that a drone had been shot down on the Afghan side of the border.
AP quoted "three intelligence officials" as saying that Pakistani troops and tribesman had shot down a suspected U.S. military drone close to the Afghan border. They said it was downed after circling the area for several hours.
AP also quoted a U.S. military spokesman in Afghanistan, Captain Christian Patterson, as saying officials were looking into the report.
Earlier on September 23, U.S. President George W. Bush said visiting Pakistani President Asif Ali Zardari had spoken strongly about protecting Pakistani sovereignty.
Bush did not address the strikes.
"Your words have been very strong about Pakistan's sovereign right and sovereign duty to protect your country, and the United States wants to help," Bush said before meeting Zardari in New York.
Pakistan's support is regarded as crucial to the success of Western forces trying to stabilize Afghanistan, and in the fight against Al-Qaeda.
But U.S. impatience has grown over what it sees as Pakistan's failure to eliminate the militant threat on its side of the Afghan border.
Pakistanis were outraged by the September 3 commando raid, the first known ground assault by U.S. troops into Pakistan, and the six-month-old civilian government issued a diplomatic protest.
General Ashfaq Kayani said foreign troops would not be allowed on Pakistani soil and Pakistan's sovereignty and territorial integrity would be defended at all costs.
Speaking to the U.S. Senate Armed Services Committee on September 23,
Defense Secretary Robert Gates warned that "the nature of the threat that they face, beginning with the assassination of the current president's wife and now most recently the attack on the Marriott hotel, makes very clear to the Pakistani government that they face an existential threat in the western part of their country."
Pakistani troops fired on two U.S. helicopters that crossed the border at the same village, Angor Adda, a week ago, forcing them to turn back, according to residents and security officers.
Pakistan and the United States issued denials.
Pakistani troops fired on two U.S. helicopters that intruded into Pakistani airspace on the night of September 21, again forcing them to turn back to Afghanistan, a senior Pakistani security official said.