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Afghans burn the U.S. flag in Herat, west of Kabul, Afghanistan, Sunday, Sept. 16, 2012, during a protest against an Internet video mocking the Prophet Muhammad that many fear could further aggravate Afghan-U.S. relations. The video has sparked protests throughout the Muslim world and the Afghan government blocked the YouTube site that hosts the video and its parent company, Google Inc., over the weekend in a move to prevent violent protests. (AP Photo/Hoshang Hashimi)

Afghan attack kills US troops

An Afghan soldier turned his gun on American troops

at a checkpoint in the country's east, killing two Americans and at

least two fellow members of Afghanistan's army in a shooting that marked

both the continuance of a disturbing trend of insider attacks and the 2,000th U.S. troop death in the long-running war. (AP)