Pakistani troops fire on US helicopters at border.

KABUL, Afghanistan - Pakistani soldiers fired at American reconnaissance helicopters that were escorting Afghan and U.S. ground troops along the volatile border Thursday, sparking a five-minute ground battle between the countries which have been allies in the war on terrorism, officials said.
Attempting to play down the incident — the first serious exchange with Pakistani forces acknowledged by the U.S. — Pakistan's president said only "flares" were fired at foreign helicopters that he said had strayed across the border from Afghanistan into his country.
The five-minute exchange, which could have easily escalated into a much bigger conflict, could heighten tensions at a time the U.S. is stepping up cross-border operations in a region known as a haven for Taliban and al-Qaida militants.
It also came as new Pakistani President Asif Ali Zardari was in New York meeting with Secretary of State Condoleezza Rice, and Afghan President Hamid Karzai was scheduled to meet with President Bush on Friday.
Two American OH-58 reconnaissance helicopters, known as Kiowas, were on a routine patrol in the eastern province of Khost when they received small arms fire from the Pakistani border post, said Tech Sgt. Kevin Wallace, a U.S. military spokesman in Bagram. There was no damage to aircraft or crew, officials said.More.