Fighting in both countries has left at least 25 people dead, including seven killed when Taliban militants in northwest Pakistan ambushed pro-government tribal elders, a NATO statement said, according to the Associated Press.
The military alliance said it fired the rounds Sunday after insurgents attacked troops in Afghanistan's eastern Paktika province with rockets from across the border.
"The artillery fire caused a secondary explosion at the rocket launch site, which indicates additional munitions in the location," the statement read.
Pakistan's military said in a statement also released Tuesday that militants attacked a NATO post Sunday and that NATO troops "engaged the fleeing militants on (the) Afghan side of the border and informed (a) Pakistani post on the Pak-Afghan border," quoted the AP.
Officials say relations between NATO-led troops in Afghanistan and Pakistan's military are improving, but Pakistan has complained about unilateral missile strikes by U.S. forces into its tribal areas, saying they violate its sovereignty.
Also along the Afghan border, Taliban militants attacked Pakistani tribal leaders, setting off a gun battle and a blast that killed seven people, said a government representative, Israr Khan, reported the AP.
The gun battle, which occurred Monday in the restive tribal area of Bajur, killed a commander of the Taliban fighters and two guards of the elders' compound, Khan said.
Four elders also died when an explosion went off in the compound, though it was unclear what caused the explosion.
In another incident in Swat Valley in northwestern Pakistan, security forces killed seven militants, and insurgents ambushed an army convoy, killing one soldier, the Pakistani army said in a statement.