KABUL -- An Afghan police officer killed at least 10 fellow officers yesterday, a day after six U.S. service members -- including Lance Cpl. Greg Buckley Jr., 21, of Oceanside -- were gunned down by their Afghan partners in summer violence that has both international and Afghan forces questioning who is friend or foe.

Attacks on foreign troops by Afghans working with the alliance are on the rise and, while cases of Afghan security forces killing within their own ranks are less frequent, together they show how battle lines have blurred in the decade-long war.

The assaults on international service members have stoked fear and mistrust of their Afghan allies, threatening to hamper the U.S.-led coalition's ongoing work to train Afghan police and soldiers. The attacks also raise questions about the quality of the Afghan forces that have started taking charge of security in many areas of the country as U.S. and NATO combat troops move to withdraw by the end of 2014.

Coalition officials say a few rogue policemen and soldiers should not taint the integrity of the Afghan security forces and that the attacks have not impeded plans to hand over security to Afghan forces, which will be 352,000 strong in a few months. But there is growing unease between international troops and their Afghan partners.

Shakila Hakimi, a member of the Nimroz provincial council, said the policeman who shot his colleagues at a checkpoint in Dilaram district is believed to have had ties to militants. He was killed in an ensuing gun battle, she said.

A day earlier, two Afghans shot and killed six American service members in two attacks in neighboring Helmand province in the south, where insurgents have wielded their greatest influence.

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