Why did Khrushchev send a second note to president JFK?

On Friday Oct. 26, 1962 Khrushchev sent two letters to President Kennedy.

The first letter was not made public. It was supposedly softer saying Russia would remove its missiles from Cuba if the U.S. would end the quarantine and garantee the U.S. would not invade Cuba. The second letter sounded harsher, seeking the removal of U.S. missiles in Turkey in return for taking Russian missiles out of Cuba.