What precipitated Russia putting missles in Cuba was the US, and NATO, putting missles in Turkey .
Not analogous to Cuba. Its analogous to an unfinished version of our Civil War.
If Florida were not peninsula, but an island, and if the United States did not have the strong navy that it had had in the 1860s then Jefferson Davis and the Confederate government could have fled to Florida, and Florida might still be the one remaining state in the Confederacy (after the other ten had fallen to the Union). And imagine if Florida's Confederate regime had lasted until now.
Today the US govt. would view Florida as a "renegade province/state" much the way Beijing views Taiwan. Imagine if say... Putin's Russian republic were to suddenly station troops in Florida. A foreign power backing up with muscle a breakaway state's claim to independence would be very provocative to Washington, because Washington would view it as Russia occupying America's own territory.