Planners decided against erecting model tent cities for migrants around rows of cinder-block bathrooms and showers the Bush administration had a contractor build in scrubby fields on the base in 2007, just in case. But there’s a razor-wire-ringed command-and-control center for Army Maj. Gen. Frederick Rudesheim — the Army South commander in charge of troops reacting to fake news reports prepared by a training unit in Norfolk, Va., featuring fake TV anchors introducing fake interviews interspersed with real historical footage.

With U.S. forces in constant rotation, “to work together in an exercise before we actually have to do it in a real world situation is very important,” said Army Col. Jane Crichton, leading the public affairs portion of the exercise — what you tell the world, what images you release.

“Exercising doing simulation is harder than what you’d do in reality,” the colonel added, because they’re compressing a potential crisis spanning weeks or months into days.

This 45-square-mile base mostly looks like a small town with a McDonalds, pleasure-boat marina and two free open-air movie theaters.

But it has long served as a U.S. military safe haven in the Caribbean.

In 2010, the State Department used its airstrip as a massive way station of relief supplies to quake-shattered Haiti. Between 1984 and 1986, Guantánamo sheltered more than 50,000 Haitians and Cubans from the golf course to a stretch of land overlooking the sea where they’d been picked up fleeing their nations.

Now the Pentagon’s prison for 166 captives has become part of the routine — run by 1,700 U.S. military and civilian contractors, atop the place that provided safe haven in the 1980s.

So on the Windward side of the base this weekend, sailors and other residents spent the weekend fishing on the bay, at the beaches or cruising the waters in recreation boats even as the base awaits $8.9 million to rebuild a marina wrecked by Hurricane Sandy.

On the Leeward side, the atmosphere bristled with purpose — flights discharged relatives of victims of the Sept. 11 attacks for the latest pre-trial hearings at the war-crimes tribunals while, just beyond the airstrip, Army South was conjuring up classified challenges of a faux migrant crisis.