First off the intelligence estimate the USA side was working with was that there were no nuclear warheads on Cuba at the time but that they were expected to arrive soon. In the early 1990s, during the brief window openness following the collapse of the USSR, a seminar was held in Russia to which senior players during the crisis were invited to share information about what had happened. Among the revelations new to the US side were first that there were in fact about 80 warheads on the island, and furthermore that about fifteen of them were tactical tactical ones that were mounted on missiles with a range of about 100 miles. These wouldn’t have reached into the US much beyond Key West or Miami, but they could have destroyed most of the US fleet closing in for a possible landing on Cuba. Can you spell casus belli? More details can be found in an appendix to one of Robert McNamara’s books, In Retrospect.