Three of the four Americans killed by an explosion in Syria on Wednesday were a soldier, a sailor and a civilian working for the Defense Department.
Army Chief Warrant Officer Jonathan R. Farmer, 37, Navy Chief Cryptologic Technician Shannon M. Kent, 35 and Scott A. Wirtz were identified by the Department of Defense as three of the Americans killed while "conducting a routine patrol" in the Syrian city of Manbij, near the Turkish border.
The fourth American killed in the blast has not been identified. The Department of Defense said Wednesday that the person was a contractor supporting the department.
ISIS claimed responsibility for the attack through recognized social media accounts, claiming a suicide bomber wearing an explosive vest attacked coalition forces. ISIS did not immediately produce evidence to support the claim.
American defense officials said that despite the claim of responsibility by the Islamic State, which is also known as ISIS, there has been little to no ISIS presence in Manbij in months, and the terror group sometimes falsely claims responsibility for attacks.
Wednesday's killing of two U.S. service members was the single deadliest day for American forces in Syria.
The attack came weeks after President Donald Trump announced in a tweet on Dec. 19, that U.S. troops would withdraw from Syria immediately.
Trump said the U.S. had "defeated ISIS in Syria," adding that was the "only reason" to have troops on the ground there.
Administration officials later said troop removal will happen more slowly.