US Army Army Major General Michael Harrison, center, observes a field exercise with members of the Japan Ground Self Defense Force in November 2010.

TOKYO – Well, this is embarrassing.

Just days after the Marines handed out wallet cards reminding troops in the Pacific to behave ethically, the Army’s top general in Japan has been effectively fired over allegations that he failed to report or properly investigate an alleged sexual assault involving his own staff.

Details have not been released, but Major General Michael Harrison, commander of U.S. Army-Japan, allegedly failed to act on reports that a member of his staff had sexually harassed and later assaulted a Japanese female whom he, the staff member, was supervising.

Harrison’s headquarters are located at Camp Zama, near Tokyo, where the Japan Self Defense Force’s elite Central Readiness Force established its own headquarters earlier this year. Harrison presided at the high-profile relocation ceremony.

The suspension is likely a career-ender for Harrison, who commanded about 2,500 Army troops in Japan and provided a key link with the JSDF. It also comes as the Army is trying to raise its profile in Asia.

Harrison’s suspension was announced June 7, just four days before he was scheduled to complete his 32-month assignment. A change of command ceremony scheduled for Tuesday was canceled and his replacement, Major General James Boozer, took over early.

“General Boozer has been here at the headquarters, meeting his commanders and staff, and is looking forward to meeting with his Japanese counterparts, as planned,” Major Kevin Toner, a spokesman for U.S. Army Japan, said Monday.

Harrison was scheduled to move up as the deputy commander of Army forces at U.S. Central Command, in Kuwait. But given the toxicity of the sexual assault issue in the military, that seems unlikely to happen now. The investigation is being directed from Washington and is likely to take several months to complete; even if Harrison were cleared, it’s unlikely the Pentagon would leave the Kuwait post unoccupied that long.

The timing is awkward for the Army, which is looking to expand its role in the Pacific. The Army has earmarked some 70,000 troops for deployment to the theater and the U.S. Army-Pacific commander, based in Hawaii, was recently elevated to four-star status.

But two-thirds of those troops are based in Hawaii or the U.S. mainland. In Japan, the Army is limited largely to logistics, training and coordination issues. The Marines, with some 18,000 troops based in Okinawa, provide the most visible U.S. ground forces in the region.