One US soldier has been killed and three others wounded in a bomb attack in the southern Afghan province of Zabul, the US military says.
The bomb exploded near an armoured vehicle in which the soldiers were travelling in Shinkay district.
The Taleban carried out the attack, said its spokesman Latifullah Hakimi.
Attacks linked to the Taleban have risen since a lull over winter. Nearly 150 US soldiers have died since US-led forces ousted the Taleban in 2001.