"Let every nation know, whether it wishes us well or ill, that we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, to assure the survival and success of liberty" was spoken by whom?

When Soviet nuclear missile sites were discovered in Cuba, Kennedy ordered a blockade of the island. For 13 days in October, 1962, the United States and the Soviet Union teetered on the brink of nuclear war. Finally, Soviet premier Nikita Khrushchev backed down.