The XX Bomber Command operating Strategic B-29 bombers of the Twentieth Air Force, which were attacking Japan in Operation Matterhorn, were forced to move as well. Although this affected their efficiency for a short time, in early 1945 the Twentieth Air Force moved to newly established bases in the Marianas under the command of the newly established XXI Bomber Command. This nullified the limited protection from U.S. bombing that the Japanese home islands had received from Operation Ichi-Go.