WASHINGTON ‚ Pakistani and American ground troops exchanged fire along the border with Afghanistan on Thursday after the Pakistanis shot at two American helicopters, ratcheting up tensions as the United States increases its attacks against Qaeda and Taliban militants sheltering in Pakistan's restive tribal areas.
The two American OH-58 Kiowa reconnaissance helicopters were not damaged and no casualties were reported on either side from the ground fire. But American and Pakistani officials agreed on little else about what happened in the fleeting mid-afternoon clash between the allied troops.
American and NATO officials said that the two helicopters were flying about one mile inside Afghan air space to protect an American and Afghan patrol on the ground when the aircraft were fired on by small-caliber arms fire from a Pakistani military checkpoint near Tanai district in Khost Province.
In response, the American ground troops shot short bursts of warning fire, which hit well shy of the rocky, hilltop checkpoint, and the Pakistanis fired back, said Rear Adm. Gregory Smith, a spokesman for the Central Command.
But a spokesman for the Pakistani army, Maj. Gen. Athar Abbas, said Pakistani forces fired warning shots at the American aircraft after they crossed into Pakistan's territory in the area of Saidgai, in North Waziristan's Ghulam Khan region. "On this, the helicopters returned fire and flew back," General Abbas said.
Local residents said that one of the two helicopters had entered inside Pakistan territory by about a mile, while the other hovered on the Afghan side of the border.
"When our forces fired warning shots, we were a little scared of a possible retaliatory fire from the helicopters," said one of the residents, Haji Said Rehman Gorbaz. "But we were happy to see the helicopter flying back into Afghanistan. We were happy that our forces fired at the helicopter."
The Pakistani president, Asif Ali Zardari, said Thursday that his nation's military had fired only flares at the helicopters, seeming to draw a distinction with warning "shots," which usually refers to bullets or other ordnance that could more seriously damage the helicopters.
"They are flares," Mr. Zardari said as he sat down to meet Secretary of State Condoleezza Rice on the fringes of the United Nations General Assembly in New York.
"They are flares just to make sure that they know they have crossed the borderline," he added, noting that the Afghan-Pakistan frontier is a rugged, ill-marked division between the two nations.
"Sometimes the border is so mixed that they don't realize that they crossed the border," Mr. Zardari said.
Ms. Rice agreed that the border between Pakistan and Afghanistan is "very, very unclear," and "one of the most inhospitable places."
But the clash drew immediate protest from Pentagon officials in Washington. "The flight path of the helicopters at no point took them over Pakistan," a Pentagon spokesman, Bryan Whitman, told reporters at a briefing.
Mr. Whitman said United States and NATO military officials were speaking to their Pakistani counterparts to determine what happened and to ensure there was no repeat, adding: "The Pakistanis have to provide us with a better understanding of why this took place."
General Abbas, the Pakistani spokesman, said the incident had been reported to NATO headquarters in Kabul and was under investigation by both Pakistani and NATO officials.
Although the incident lasted just a few minutes, military officials and diplomats said the brief clash showed there was a risk of a much more serious, and lethal, misunderstanding along the border.
Pakistani civilian leaders have denounced an incursion by American Special Operations forces into Pakistan on Sept. 3, which was authorized under orders given by President Bush in July, and the Pakistani Army has vowed to defend its border "at all costs."
"We will not tolerate any act against our sovereignty and integrity in the name of the war against terrorism," Pakistan's prime minister, Yousaf Raza Gilani, told reporters on Wednesday. "We are fighting extremism and terror not for any other country, but our own country."
The latest clash on Thursday comes after a week of claims by Pakistani intelligence officials that American helicopters had strayed across the border from Pakistan, and that an American pilotless surveillance aircraft had crashed, apparently due to mechanical failure, on Pakistani territory.
American officials denied these claims, saying they were being manufactured by Pakistani officials in response to rising anti-American sentiment in Pakistan following the increased American activities in the border area.
