U.S. Marines have killed more than 80 insurgents during a three-week assault on a Taliban stronghold in southern Afghanistan, the military said Saturday. The tally highlights the fighting that has engulfed parts of the country's south.

"The Marines have been aggressive, relentless and successful," Lt. Col. Tucker Mansager, a U.S. military spokesman, said. "They have demonstrated that there is no refuge for the terrorists." Only two Marines have been wounded in the latest fighting, the U.S. military said.

American commanders sent about 2,000 Marines into Afghanistan in the spring, boosting the U.S.-led force to 20,000 in an attempt to put insurgents on the defensive ahead of September elections.

Insurgents have stepped up their own operations, fueling a spiral of violence that has killed more than 450 people across the country this year.

In neighboring Pakistan, Pakistani troops backed by helicopter gunships and fighter jets searched mountains and skirmished with Islamic fighters Saturday as they closed in on a cluster of suspected al Qaeda hideouts and a training facility near the Afghan border.

The offensive focused on three compounds linked to al Qaeda -- a training facility, a safe house, and the home of an alleged terror financier -- near the town of Shakai, about 15 miles west of Wana, the largest town in South Waziristan province.

On Friday, Pakistani army spokesman Maj. Gen. Shaukat Sultan said troops launched the operation in response to "unprovoked firing" by foreign fighters. He said the army killed 35 insurgents on Wednesday and Thursday.

Pakistani forces used artillery and helicopter gunships Friday against rebels near Shakai, the security official said, speaking on condition of anonymity. Pakistani forces met little opposition, he said.

In Kabul, Mansager said American forces were in "very close contact" with Pakistani troops about the operation and sharing information.

"We maintain a very robust presence on that portion of the border in anticipation of any anti-coalition militants that might try to escape the Pakistani army across the border," Mansager told reporters.

In Afghanistan, U.S. troops on Friday detained a bomb maker about 40 miles south of Kabul, Mansager said.

The U.S. military and international peacekeepers based in Kabul have been warning since last year that Islamic fighters are using the kind of roadside bombs that have proved so deadly in Iraq.

Seven American troops have been killed in southern Afghanistan since early May and dozens of Afghan soldiers have died in the region this year.

The Marines, based in Uruzgan, the home province of fugitive Taliban leader Mohammad Omar, called in warplanes to pound a large group of suspected fighters in nearby mountains. At least 20 people reportedly died in a clash last week.

Most of the fighting has been near Daychopan, in neighboring Zabol province. Mansager said the Marine offensive was allowing Army troops to focus on building ties with local communities across the troubled border region. Commanders said they hope this approach, which includes offering millions of dollars in reconstruction aid, will persuade villagers and tribes to turn against the insurgents and provide intelligence.

Khan reported from Peshawar, Pakistan.

Pakistani army soldiers patrol on the outskirts of Wana, where they have launched an offensive against several compounds linked with Al Qaeda.