Monday's death was the 17th U.S. combat death in Afghanistan this year, according to the Pentagon's count. There also have been three non-combat deaths this year. More than 2,400 Americans have died in the nearly 18-year war.
Across Afghanistan, militant attacks and more violence killed at least seven people as the country prepares for presidential elections later this month, Afghan officials said. At least five civilians, including women and children, were killed when their vehicle struck a roadside bomb in western Farah province on Sunday, according to Mohibullah Mohib, spokesman for the provincial police.
No one immediately claimed responsibility for the bombing, which occurred near the city of Farah, the provincial capital, but the Taliban are active in the province. Earlier this month, the Taliban launched an attempt to take the city of Farah, briefly seizing an army recruitment center and setting it on fire. Airstrikes were called in and the Taliban were eventually forced out of the city.
Separately, a magnetic explosive device attached to a mini bus belonging to a university in Ghazni province exploded and killed the bus driver. Arif Noori, spokesman for the provincial governor, said five Ghazni University students were also wounded in the blast.
In eastern Logar province, a schoolgirl died in the crossfire during a battle in the Mohammad Agha district between the Taliban and the security forces, the police said. A second student was wounded. Afghan president Ashraf Ghani cancelled his first electoral debate with his main electoral rival, Abdullah Abdullah, the country's chief executive. Both men are partners in the national unity government.
Ghani's electoral team, in a statement released just before the start of the debate, claimed Abdullah has no political program and that Ghani did not want to debate him. Abdullah, who was present at the TV studio where the debate was to be held, said Ghani "should have come and shared his plans."
Around 100,000 members of the country's security forces will provide security on election day, Sept. 28. Around 72,000 security personnel will be on duty around the 4,942 polling centers across Afghanistan while nearly 30,000 additional troops will serve as reserve units.
Approximately 20,000 American and allied troops remain in Afghanistan. Between 14,000 and 13,000 U.S. troops are currently in the country.
Associated Press writer Robert Burns in Washington contributed to this report.