On 18 May 1972, Queen Elizabeth II visited the Windsors while on a state visit to France; she spoke with the Duke for fifteen minutes, but only the Duchess appeared with the royal party for a photocall as the Duke was too ill.
Nixon used the improving international environment to address the topic of nuclear peace. Following the announcement of his visit to China, the Nixon administration concluded negotiations for him to visit the Soviet Union. The President and First Lady arrived in Moscow on May 22, 1972 and met with Leonid Brezhnev, the General Secretary of the Communist Party; Alexei Kosygin, the Chairman of the Council of Ministers; and Nikolai Podgorny, the head of state, among other leading Soviet officials.Nixon engaged in intense negotiations with Brezhnev. Out of the summit came agreements for increased trade and two landmark arms control treaties: SALT I, the first comprehensive limitation pact signed by the two superpowers, and the Anti-Ballistic Missile Treaty, which banned the development of systems designed to intercept incoming missiles. Nixon and Brezhnev proclaimed a new era of "peaceful coexistence". A banquet was held that evening at the Kremlin.
On May 24, 1972, Nixon approved a five-year cooperative program between NASA and the Soviet space program, culminating in the 1975 joint mission of an American Apollo and Soviet Soyuz spacecraft linking in space.