BAGHDAD (AP) — Iran's Revolutionary Guard says a U.S. drone strike has killed two of its advisers in Iraq, though the U.S. said Monday it has only struck militants in its campaign against the Islamic State group.The claim came as negotiators on Monday attempted to reach a deal on Iran's contested nuclear program, which hard-liners in the Islamic Republic have opposed as giving away too much to the West.The Guard said on its sepahnews.ir website the strike happened March 23, just after the U.S.-led coalition began airstrikes to support Iraqi forces trying to retake the Islamic State-held city of Tikrit.