Even when Japanese businessmen pressed for closer relations with China in 1970, the Japanese prime minister, Eisaku Sato, staved them off out of deference to the U.S. policy of containing China.

WSJ: A Dangerous Rift Between China and Japan

One secret pact signed in 1969 by President Nixon and Japanese Prime Minister Eisaku Sato allowed the U.S. to reintroduce nuclear weapons into Okinawa in times of emergency, and with prior consultation with Japan.

NPR: Japan Confirms Secret Nuclear Pacts With U.S.