Please cite the treaty under which Guantanamo Bay is US Territory. No such treaty exists! Unlike diplomatic missions (e.g., embassies and consulates), that are deemed to be the territory under whatever flag they fly, the terms and conditions of military bases are negotiated. Cuba has been claiming that the US occupation of Guantanamo Bay is invalid under several treaties and, furthermore, that the US operations violate the original treaties should they deemed to be valid.
Under your definition, Iraq and Afghanistan are "US Territory", which, I am sure, is preposterous.