WASHINGTON — U.S. and Pakistani forces exchanged gunfire Thursday along the Afghan border, military officials said, as tensions over American incursions into Pakistan flared.
The incident began, U.S. officials said, when forces from a Pakistani outpost fired on two Kiowa OH-58 reconnaissance helicopters. That touched off a five-minute small-arms fight when a ground unit made up of Afghan and U.S. forces returned fire, U.S. military officials said.
There were no casualties, the officials said. The shots fired by the U.S.-Afghan unit were "suppressive," intended to force the Pakistanis to take cover and stop shooting. The helicopters did not fire, the officials said.
U.S. military officers said the helicopters, under the command of North Atlantic Treaty Organization forces, never left Afghan territory. But Pakistani officials said the helicopters crossed the border and entered Pakistan's tribal regions.
Although Pakistani officials have reported their military firing on U.S. helicopters and unmanned aircraft in recent weeks, the incident Thursday marks the first time U.S. officials have confirmed an attack by Pakistani forces.
Anger in Pakistan has been rising since the U.S. began conducting additional cross-border commando raids as well as stepping up the number of attacks from unmanned Predator drones in the tribal areas.
American officials said they did not believe senior Pakistani army officers had issued formal orders to fire on U.S. military units that cross the border. Defense officials said they may never know why the Pakistani forces fired, but some think troops may have been influenced by anti-American rhetoric from the government.
The two sides' accounts differ sharply. U.S. military officials said the helicopters were flying in support of the small ground force, which was conducting "routine operations" on the border.
Pakistani officials said the choppers entered deep into Pakistani airspace and flew over the North Waziristan tribal area for 20 minutes. Residents said unmanned spy planes were still hovering over the area.
The Pakistani army's Inter-Services Public Relations said two helicopters from Afghanistan crossed into Pakistani territory near the Ghulam Khan sector, prompting warning shots from the outpost.
U.S. officials contended that their forces never left Afghanistan's Khowst province, and they denied that the helicopters fired on the Pakistani outpost, saying the only U.S. gunfire came from ground forces.
At the United Nations, Pakistani President Asif Ali Zardari said his troops fired only flares at the aircraft. In an address to the General Assembly, he said, "We cannot allow our territory and our sovereignty to be violated by our friends."
Tensions surged after a Sept. 3 raid into the South Waziristan tribal region by U.S. special operations forces, which prompted protests and a formal condemnation by the Pakistani parliament. A week later, Gen. Ashfaq Kayani, the Pakistani army chief of staff, who has been courted by Pentagon officials, criticized such U.S. operations.
A Pakistani army spokesman, Maj. Gen. Athar Abbas, told the Associated Press that troops should "open fire" to prevent military forces from crossing the border. U.S. officials said they did not believe Abbas' remarks represented official policy.
In Thursday's incident, Western military officers in the region reported that the helicopters were about a mile inside the Afghanistan border. But there are frequent disagreements about the precise location of the border.
Bryan Whitman, a Pentagon spokesman, said the incident was a misunderstanding. But he suggested that the Pakistanis should have had little doubt whom they were firing at. "We know the challenges on the border, but it is not too difficult to imagine who is flying helicopters there," he said. "Pakistan is an ally, not an enemy."
After the incident, U.S. military officials in the region scrambled to meet with Pakistani military liaisons.
Meanwhile, citing concerns about security in Pakistan, the State Department said it had temporarily suspended its consular activities, mainly processing and issuing visas.
"We're very concerned about the security situation," said Robert Wood, a department spokesman.
Times staff writers Geraldine Baum at the United Nations and Henry Chu in London and special correspondent Zulfiqar Ali in Peshawar, Pakistan, contributed to this report.