A US soldier was killed and another was wounded in a clash with militants which left seven Taliban fighters dead in southern Afghanistan, the American-led coalition said. US and Afghan forces exchanged fire with 20 militants in Helmand province, before calling in aerial support that resulted in the dropping of 11 guided-bombs, the coalition said in a statement.An Afghan soldier was also wounded. A purported spokesman for the Taliban, Yousuf Ahmadi, said by telephone that the movement's fighters had been involved in the battle in Sangin district, confirming that one of its men had been wounded in the clash. Authorities in Sangin, a hotbed for Taliban activities, confirmed details of the clash.