While Khrushchev was sending blustering messages to Kennedy, he was what?

The Cuban Missile Crisis took place from October 16 to October 28, 1962. At the same time Khrushchev was sending threatening messages to President Kennedy, he was also delivering nuclear-enhanced ballistic missiles to Cuba. For a while, it looked like the crisis would spiral out of control, but finally, on October 26th, Khrushchev sent a message to Kennedy telling him he would pull the missiles out of Cuba if the United States agreed to not invade Cuba.