What if China ran their war ships into Mexico gulf just like U.S did in Southern China Sea?We shall think it is quiet fair because in the "public" ocean?
Russia was just busy flying bombers 40 miles off the coast of California last week. Last time I checked, we haven't declared war on Russia for it. They regularly do the same thing with their navy in various ways, whether off the Atlantic or Pacific coast, or near Cuba / Florida waters.
The proper comparison to cuba is Star Wars type missile shields. And USSR/Russia has long been quite opposed to that, for good reason.
SLBMs were just being developed in the early 60s, and so Cuban-based missiles represented a novel, more credible first-strike threat given distance (~20 minutes flight time).