"
A Pakistani border scout opened fire with a G-3 rifle
after the US patrol asked him to return to the Pakistan
side of the border.
"
US military statement
A statement said that a B-52 dropped a bomb near the border town of Shkin after a Pakistani guard opened fire and wounded an American soldier.
He started shooting after being asked to return to his side of the border.
US forces regularly patrol the area looking for suspected al-Qaeda or Taleban forces.
Locals say the bombs fell on an abandoned Islamic seminary in the village of Burmol, in Pakistan's South Waziristan district.
Sensitive border
The US soldier who was injured has been transferred to a military hospital in Germany.
His condition is not serious.
It was not clear why the Pakistani soldier had opened fire in the incident, which took place on Sunday.
The area was the scene of a gunbattle last week in which an American soldier died after US forces came under attack while on night patrol.
He was the first American to be killed in Afghanistan on active duty for seven months.
The attackers are reported to have fled across the border into Pakistan.
Pakistan has pledged to clamp down on the movement of suspected al-Qaeda and Taleban members across the border in order to help the US war on terror.
Arms find
In another development, international peacekeepers in the Afghan capital, Kabul, have seized a large cache of weapons at a house in the city.
The weapons included 88 mortar rounds and 30 rocket-propelled grenades, according to a spokesman for the International Security Assistance Force (Isaf).
Isaf said the cache had been removed and would be destroyed.
It was unclear who owned the weapons.