Private First Class Hansen Kirkpatrick, 19, of Wasilla, Alaska died Monday following the "indirect fire" assault, which means he was hit by a mortar or some other incoming round.

The wounds sustained by the two soldiers were not considered life threatening, and they were being treated at a coalition medical facility, US Forces-Afghanistan said in a statement.

Pentagon spokesman Navy Captain Jeff Davis said the soldiers had been conducting an off-base operation with partnered Afghan security forces when they came under fire.

It was "presumably" a Taliban attack, he said.

"No reason to believe it's anything other than that," Davis added, noting that the incident occurred in the Nawah district of Helmand.

Pentagon chief Jim Mattis is expected to present President Donald Trump this month with a revamped Afghanistan strategy aimed at breaking a stalemate with the Taliban.

Currently about 8,400 US troops are in Afghanistan along with about 5,000 NATO forces.

Mattis is weighing deploying thousands of additional troops to work with more Afghan combat units.