KABUL, Afghanistan (AP) - Senior US military officials say an Afghan teenager has killed an American soldier in eastern Afghanistan by stabbing him in the neck.

Two officials said on Monday that Sergeant Michael Cable, 26, was guarding a meeting of Afghan and US officials in Nangarhar province when the stabbing occurred.

One of the officials estimated that the attacker was 16 years old, but he escaped so the age could not be verified.

The official says the youth was not believed to be from the Afghan security forces so the Wednesday stabbing is not being classified as an insider attack.

Both officials spoke on condition of anonymity because the investigation is ongoing.

The Pentagon said last week that Sgt Cable died from injuries sustained when his unit was attacked by enemy forces.