April 12, 1961
THE PEOPLE of the United States share with the people of the Soviet Union their satisfaction for the safe flight of the astronaut in man's first venture into space. We congratulate you and the Soviet scientists and engineers who made this feat possible. It is my sincere desire that in the continuing quest for knowledge of outer space our nations can work together to obtain the greatest benefit to mankind.
JOHN F. KENNEDY
[N. S. Khrushchev, Chairman, Council of Ministers, Union of Soviet Socialist Republics]
John F. Kennedy, Message to Chairman Khrushchev Concerning the Flight of the Soviet Astronaut. Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/234586