WASHINGTON (AP) — Iranian jets have carried out airstrikes against Islamic State militants in Iraq in recent days, Pentagon officials and independent analysts say, underscoring the strange alliances generated by the war against the extremist group that has beheaded Americans and killed and terrorized Iraqi civilians.Washington and Tehran are locked in tough negotiations over Iran’s nuclear program. But the two adversaries have been fighting parallel campaigns on the same side in Iraq to defend the Shiite-dominated government — and the region’s Kurds — from IS militants who seized a large section of the country.It has long been known that Iranian troops and advisers have been fighting alongside Iraqi forces, but until this week there had been no confirmation of Iranian air activity. The timing and nature of the strikes are not clear, but a senior U.S. official said they occurred in Diyala province, which extends from northeast Baghdad to the Iranian border.