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U.S. texts 'prove secret deal' / Show Japan-U.S. agreement on Okinawa reversion, N-weapons
http://www.yomiuri.co.jp/dy/national/20071007TDY01305.htm

Japan and the United States reached a secret agreement to allow the United States to bring nuclear arms into Japanese territory in exchange for the return of the U.S.-occupied Okinawa islands in 1972, according to declassified U.S. government documents.