Kennedy replied by reinforcing the Berlin garrison and increasing the Nation's military strength, including new efforts in outer space. Confronted by this reaction, Moscow, after the erection of the Berlin Wall, relaxed its pressure in central Europe. Instead, the Russians now sought to install nuclear missiles in Cuba. When this was discovered by air reconnaissance in October 1962, Kennedy imposed a quarantine on all offensive weapons bound for Cuba. While the world trembled on the brink of nuclear war, the Russians backed down and agreed to take the missiles away. The American response to the Cuban crisis evidently persuaded Moscow of the futility of nuclear blackmail. Kennedy now contended that both sides had a vital interest in stopping the spread of nuclear weapons and slowing the arms race--a contention which led to the test ban treaty of 1963. The months after the Cuban crisis showed significant progress toward his goal of "a world of law and free choice, banishing the world of war and coercion." His administration thus saw the beginning of new hope for both the equal rights of Americans and the peace of the world. .