Doesn't matter. The USA does not have the right to maintain forts on the territory of Foreign Nations who don't want us there, and more than China has the right to maintain Forts on US territory.
If a Foreign Nation does not want us on their land, we can't "send supplies" or troops or anything else. Morally, we must evacuate immediately, and nothing else -- after all, it's their country; not ours.
So does that mean that Castro can demand we leave Cuba, and if we refuse he can bombard Guantanamo Bay into surrender and you would support him?