It is pretty well known that during World War II, the Japanese military ran brothels for their servicemen by forcing women of other nations to sell their bodies.
But after World War II, the Japanese government apparently opened up similar facilities for use by US military.
Of particular note:
The U.S. occupation leadership provided the Japanese government with penicillin for comfort women servicing occupation troops, established prophylactic stations near the RAA brothels and, initially, condoned the troops’ use of them, according to documents discovered by Tanaka.
Occupation leaders were not blind to the similarities between the comfort women procured by Japan for its own troops and those it recruited for the GIs.
A December 6, 1945, memorandum from Lt. Col. Hugh McDonald, a senior officer with the Public Health and Welfare Division of the occupation’s General Headquarters, shows U.S. occupation forces were aware the Japanese comfort women were often coerced.
"The girl is impressed into contracting by the desperate financial straits of her parents and their urging, occasionally supplemented by her willingness to make such a sacrifice to help her family," he wrote. "It is the belief of our informants, however, that in urban districts the practice of enslaving girls, while much less prevalent than in the past, still exists."