July 18, 1961 - The United States has warned the Soviet Union that it will defend its rights in Berlin. In a note to Moscow, the U.S. stated: "There is no reason for a crisis over Berlin. If one develops it is because the Soviet Union is attempting to invade the basic rights of others." The note declared that the U.S. was determined to defend its legal rights in West Berlin against any attempt by the Soviet Union to abrogate them, "because the freedom of the people of West Berlin depends upon the maintenance of those rights." The U.S. rejected a thesis of Premier Khrushchev that Western rights in West Berlin would be terminated if the Soviet Union carried out its threat to sign a separate peace treaty with Communist East Germany. These rights, the U.S. said, derive from the "unconditional surrender of Nazi Germany" and agreements signed during the war and after by the four occupying powers. They cannot be unilaterally abrogated by the Soviet Union, the note declared.