American planes, aiding ground troops, bombed positions Monday in southern Afghanistan as part of an operation that has killed at least 15 suspected Taliban (search) fighters, the U.S. military said.

There were no reported casualties among U.S. or Afghan troops in the fighting that began a day earlier in Kandahar province and has been dubbed Operation Mountain Viper (search), said a statemen attack Saturday as they patrolled near a U.S. base in Paktika province, a few miles from the border with Pakistan, the American military said in a statement.

The guerillas, believed to be Al Qaeda (search) or remnants of the Taliban, traded fire with the U.S. troops for about an hour before fleeing toward the Pakistan border. There were no reported casualties.

The battle was the latest in a series in the south and east of the country that suggests a growing boldness by Taliban and their Al Qaeda allies.

Suspected Taliban militants in the neighboring province of Paktia have recently threatened to cut off the nose of anyone who listens to music or men who shave their beards -- violations of their strict interpretation of Islam, said Provincial Governor Asadaullah Wafa.

Mohammed Yar, a man who lives in the province, said about 200 Taliban militants visited a local bazaar Saturday and issued a similar warning, distributing leaflets threatening "heavy punishment" for anyone who cooperates with U.S. forces in the rugged border region.

In another attack Saturday, two rockets landed near a U.S. base in neighboring Khost province, said a statement issued in Bagram, the headquarters for American forces in Afghanistan.

In Islamabad, Pakistan Foreign Ministry spokesman Masood Khan said "the backbone of the terrorists has been broken," but a small number of Taliban and Al Qaeda have regrouped.

"We should arrest, neutralize all terrorism ... in the bordering area of Pakistan-Afghanistan," he said, calling for better cooperation among U.S., Afghan and Pakistani forces in the area.

Officials have said they suspect militants have increased their activities to mark the second anniversary of the Sept. 11 attacks, which prompted the U.S.-led operation that swept the Taliban from power at the end of 2001.

In Belgium on Monday, NATO Secretary General Lord Robertson said the alliance is considering a U.S. and German request for the U.N. peacekeeping force in Afghanistan to spread outside the capital, Kabul.

NATO currently provides 5,500 troops in Kabul under a U.N. mandate to maintain order in the capital and support the Afghan authorities. About 11,500 foreign troops are also in Afghanistan in the U.S. force fighting the remnants of the Taliban and Al Qaeda.

Widening the role of the U.N. force could ease pressure on U.S. forces stretched by operations in Afghanistan and the occupation of Iraq.