The Russian president says it would "significantly change" the nature of the Ukraine conflict and amount to "nothing less than direct involvement of NATO countries".
It's worth noting that Fidel couldn't have pressed the button even if he wanted to, because the nukes were under the direct control of the USSR. At one point he did sendt a telegram to Khrushchev saying to launch the nukes if the US invaded Cuba, and IIRC Robert MacNamara later recounted that Fidel told him he would have approved of the use of tactical nuclear weapons.
It's worth noting that Fidel couldn't have pressed the button even if he wanted to, because the nukes were under the direct control of the USSR. At one point he did sendt a telegram to Khrushchev saying to launch the nukes if the US invaded Cuba, and IIRC Robert MacNamara later recounted that Fidel told him he would have approved of the use of tactical nuclear weapons.