WASHINGTON, March 27 (Reuters) - The United States will not back away from its nearly eight-year-old deployment to Syria, where it is battling the remnants of Islamic State, despite attacks on U. retaliatory air strikes and exchanges of fire that a Syrian war monitoring group said killed three Syrian troops, 11 Syrian fighters in pro-government militias and five non-Syrian fighters who were aligned with the government. Iran has been a major backer of Syrian President Bashar al-Assad during Syria's 12-year conflict