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.  Seeking to foster better relations with the United States, both China and the Soviet Union cut back on their diplomatic support for North Vietnam and advised Hanoi to come to terms militarily. Nixon later described his strategy:  I had long believed that an indispensable element of any successful peace initiative in Vietnam was to enlist, if possible, the help of the Soviets and the Chinese. Though rapprochement with China and detente with the Soviet Union were ends in themselves, I also considered them possible means to hasten the end of the war. At worst, Hanoi was bound to feel less confident if Washington was dealing with Moscow and Beijing. At best, if the two major Communist powers decided that they had bigger fish to fry, Hanoi would be pressured into negotiating a settlement we could accept.  Having made considerable progress over the previous two years in U.S.-Soviet relations, Nixon embarked on a second trip to the Soviet Union in 1974. He arrived in Moscow on June 27 to a welcome ceremony, cheering crowds, and a state dinner at the Grand Kremlin Palace that evening. Nixon and Brezhnev met in Yalta, where they discussed a proposed mutual defense pact, detente, and MIRVs. While he considered proposing a comprehensive test-ban treaty, Nixon felt he would not have time as president to complete it. There were no significant breakthroughs in these negotiations.

Answer this question "Can you tell me more about his visit to the SO?" by extracting the answer from the text above.
There were no significant breakthroughs in these negotiations.