The air strikes were called in fighting that killed some 20 Taliban rebels at a newly discovered camp in the Arghistan district of Kandahar province, about 120 miles southwest of the capital, Kabul, provincial military commander Khan Mohammed said.
American spokesman Lt. Col. Tucker Mansager said a U.S.-led patrol encountered a group of militants in the area after nightfall. Engaged in a firefight, the troops called in warplanes "for a show of force."
"When that did not work, (the planes) used precision ordnance," Mansager told reporters. "Based on the fact that the engagement ended immediately after that, it would appear that it was successful."
He said no American soldiers were hurt and that troops were searching the area Wednesday for enemy casualties.
Mansager said he had no information on the involvement of Afghan troops in the incident, but Khan said the airstrike followed an assault by about 150 of his men on a Taliban camp on a rough mountainside.
The clash appeared to be the most deadly since American-led forces and insurgents stepped up operations in the spring, fueling a spiral of violence that has left more than 350 people dead this year and cast a shadow over plans for national elections in September.
U.S. troops were also attacked on Monday, but there were no casualties, the military said. A Norwegian peacekeeper died Sunday in a rocket attack in Kabul claimed by a purported Taliban spokesman.
Elsewhere on Wednesday, a bomb or mine exploded near a U.N. vehicle as it crossed a bridge in northern Afghanistan, but no one was injured, officials said.
United Nations spokesman David Singh said the blast in Taloqan, 160 miles north of the capital Kabul, in Takhar province, appeared to have been caused by a homemade bomb.
But Faizullah, an Afghan Defense Ministry official in Taloqan, said an old mine had exploded accidentally as the vehicle was passing along a road next to a river.
There have been a spate of bombings and shooting attacks on officials helping the United Nations organize Afghanistan's first post-Taliban elections, slated for September.
Most of the incidents have occurred in the south and east of the country, where Taliban-led militants also have killed dozens of Afghan soldiers and officials in a campaign that the U.S. military says is designed to disrupt the vote.
In the most serious attack on the U.N., two British security contractor selecting sites for voter registration in eastern Nuristan were shot dead on May 5. Taliban militants claimed responsibility.
Incidents involving old mines and shells are also common in Afghanistan, which is littered with weapons left behind after more than 20 years of fighting.
The top U.S. general here has vowed to crush anti-government militants, who also include followers of fugitive warlord Gulbuddin Hekmatyar, this year with a combination of military might and reconstruction aid to persuade ordinary Afghans to turn their back on the militants and support the faltering peace process.
The United States itself has about 15,000 troops in Afghanistan, most of them attempting to hunt down remnants of al-Qaida and the Taliban in the border area with Pakistan.
Along with NATO-led peacekeepers, the U.S.-led combat force has pledged to help ensure security for the country's first post-Taliban elections slated for September.
But President Hamid Karzai says those elections could be jeopardized unless the private militias that control much of the country are disarmed.
More than 2½ years after the demise of the Taliban regime, regional warlords battle constantly over turf and narcotics trafficking.
Mark Schneider of the International Crisis Group, a research foundation, says security in Afghanistan "affects everything from elections to reconstruction. … This is not a post-conflict situation; an unrelenting battle continues in Afghanistan."
American officials are pleased with the upward trend in assistance promises. They cite the accomplishments of outside aid: 25 million school textbooks distributed, 203 schools constructed or rebuilt, 140 health clinics rehabilitated and 4.26 million children vaccinated against measles and polio.
They also tout the restoration of the war-ravaged, 310-mile Kabul-Kandahar highway. That trip, once a bone-jarring 12-hour adventure, now takes about four hours.
But the international largesse may prove meaningless unless the country's continued violence can be controlled.
"Without bringing security to Afghanistan, nothing else is possible," says Sen. Joseph Biden of Delaware, the ranking Democrat on the Senate Foreign Relations Committee.
No one doubts the distance the world's second-poorest country has to travel. A recent study by the NYU center says average life expectancy is 43 years and that one out of four children dies before age 5.