A US soldier was killed in Afghanistan on Wednesday when a member of the Afghan forces opened fire on Nato troops in the east of the country.
A Nato statement confirmed that one of its soldiers had died without stating the person's nationality, but an eyewitness and official had earlier said the Afghan had opened fire on three US troops before he was shot dead.
A US official confirmed to the Associated Press the Nato soldier was an American.
The incident took place after a meeting between Afghan provincial leaders and a US embassy official in the compound of the provincial governor in the city of Jalalabad, according to General Fazel Ahmad Sherzad.
It is the second insider attack of 2015. An Afghan soldier killed three US contractors on 29 January before he too was shot dead.
Sherzad, who is police chief for eastern Nangarhar province, said the incident happened immediately after the meeting and the embassy official had left.
"Right after the US official had left, suddenly an Afghan army soldier opened fire on the US soldiers who were present in the compound," he said.
US troops returned fire, killing the assailant, whom Sherzad identified as Abdul Azim from Laghman province.
The motive for his attack was not immediately known.