The latest attack took place in Lashkar Gah, the capital of Helmand Province, when US troops were accompanying Afghan soldiers, the Pentagon said in a statement, adding that six Afghan soldiers were also wounded.
In January, a US service member was killed in Helmand Province, a restive part of the country known as the birthplace of the Taliban, Xinhua news agency reported.
In the statement, the Pentagon expressed its deepest sympathies to the families and friends of those involved.
The attack came one day after the NATO-led mission announced that around 100 US troops had been dispatched to Lashkar Gah in the wake of the Taliban's recent seizure of nearby areas.
