In January 1961, Soviet leader Nikita Khrushchev declared his support for wars of national liberation. Kennedy interpreted this step as a direct threat to the "free world". On February 15, 1961, the President asked Soviets to avoid interfering with United Nations pacification of the Congo Crisis. Khrushchev proposed to amend the United Nations Charter by replacing the position of Secretary-General with a three-person executive called the Troyka (Russian: "group of three"). On September 25, 1961, Kennedy addressed the United Nations General Assembly, revealing his commitment to veto the Troyka plan. On February 27 of that year, in his letter to Khrushchev, the President offered an early summit meeting. Khrushchev agreed to meet in the Austrian capital Vienna. The subsequent Vienna summit was tainted by the Bay of Pigs Invasion. Khrushchev, however, tended to attribute the responsibility for the invasion not to Kennedy, but to his subordinates.