Western military officials said Saturday they were investigating Taliban claims that an Afghan soldier shot and killed at least two U.S. troops, then escaped and defected to the insurgency.
If this proves to be the latest instance of a member of the Afghan security forces turning his weapon on Western mentors, the incident comes at an awkward time. The eventual hand-over of security responsibilities to Afghan forces will be a major theme at a NATO summit in Lisbon this month.
The North Atlantic Treaty Organization force confirmed that two Western service members were killed Thursday evening in the volatile Sangin district of Helmand province. But by Saturday evening, a full 48 hours later, the circumstances of the deaths had not been disclosed.
U.S. Army Maj. Michael Johnson, a spokesman for the coalition, said details would not be released until a joint investigation by Afghan officials and the Western military had been completed.
A Taliban spokesman, Qari Yousaf Ahmadi, said an Afghan soldier shot and killed three "U.S. invaders" inside a military installation in Sangin, then fled and joined up with the insurgent forces.
The discrepancy between the two dead reported by NATO and the three claimed by the Taliban could not immediately be reconciled, although the insurgents often make exaggerated claims of Western casualties. It was also unclear whether the attack was premeditated, or if the Afghan soldier in question had been planted as an infiltrator.
Issues of trust periodically surface in dealings between Western forces and their Afghan counterparts. With training and recruitment accelerating as the U.S. looks to its exit strategy, NATO and Afghan troops live and train alongside each other at bases across the country, with weapons readily at hand.
In August, two Spanish paramilitary police officers and their interpreter were shot and killed by an Afghan at a police training center in the north of the country. In July, an Afghan soldier killed three British troops in the south, and another killed two U.S. military contractors at a base in the north earlier that month.
U.S. forces earlier this year took command in Sangin, one of the most dangerous districts in Helmand province, which in turn is one of Afghanistan's most hotly contested battlefields. Before Britain handed over responsibility for Sangin to the U.S., the district had accounted for roughly one-third of British fatalities in the course of the 9-year-old war.
With Western troop deaths this year at their highest levels since the start of the conflict, the NATO force Saturday reported the deaths of two more service members, one in the south and one in the east. It did not provide their nationalities.
The heightened tempo of fighting comes against a backdrop of continuing turmoil surrounding September's parliamentary elections.
Nearly two months after the vote, final results have not yet been released, and thousands of fraud complaints are still pending. On Saturday, the Electoral Complaints Commission said cases involving 413 candidates, including 61 incumbent members of parliament, were being referred to the attorney general's office for possible criminal investigation.