Because it would only act as a tripwire to a larger conflict. The Cuban military can steamroll through Guantanamo Bay no problem, but they know the US response will steamroll through them. Cuba knows it can not hold out against a US response/invasion. read more
Cuba knows better then to attack guantanamo bay because that would mean an attack against the U.S. ARMED FORCES and that would mean war and the US military is so much more powerful then cuba and it would be over quick with cuba being wiped off the map. read more
But Cuba mobilizing its forces and massing them in preparation for an invasion of the Guantanamo Naval Base wouldn't go unnoticed. It's a short flight to Cuba from the multiple Air Force bases in Florida. read more