GUANTANAMO BAY NAVY BASE, Cuba - U.S. troops blare The Star Spangled Banner across this 45-square-mile base each morning at 8 o'clock sharp. Fireworks crackle overhead on the Fourth of July.

Marines control the fenceline opposite Cuba's minefield and American sailors check visitors' passports or Pentagon ID cards as they arrive by plane hair transplant.

So why then did U.S. officials recently advise some Chinese journalists who report from Washington that, by traveling to Guantanamo as guests of the Pentagon, they would see their visas to visit and work in the United States expire?

The answer is that, while the U.S. Navy base functions like an extension of the United States, sometimes it is and sometimes it isn't - mostly to the benefit of those in government.

Consider this: Defense Department contractors who work and live here and don't set foot onto U.S. soil for more than 30 days a year get a tax break, like any American living and working abroad.

Army guards at the prison don't get the tax exclusion, but they do get bonuses of $425 a month in allowances, imminent danger and hardship duty pay - plus $250 a month if they leave family behind.

Scuba, Pizza Hut, DUI checkpoints

Those dollars buy time scuba diving, Pizza Hut delivery and drinks in the base bars, all Navy-run enterprises, office furniture as are the free rides home to avoid the base's drunk-driving checkpoints.

Navy base and prison guests are put up in two-story townhouses that ooze American - patios for barbecues, a downstairs powder room for guests, private laundry rooms. But over at "Camp Justice" - the place where the Pentagon is putting on the death-penalty trials - visitors are put up in a crude tent city evocative of Bagram airbase in Afghanistan circa 2001.

It all creates a certain dissonance, says retired Army Lt. Col. Chris Jenks, who observed some Sept. 11 pretrial hearings recently, his first foray back to "the battlefield" since leaving service and becoming a law professor at Southern Methodist University in Dallas.

At one moment, the West Point grad said, you can see families at McDonald's or the bowling alley or take a sunset sail on the bay. But the war court compound where he was put up was so reminiscent of his last forward operating base in Iraq that one morning he groggily reached for his M16 in the latrine tent, and briefly panicked because it wasn't there.

Guantanamo, he says, is made up of "puzzle pieces from three or four sets" that don't fit together.

Perplexing precedents

Jenks is a former infantryman turned lawyer in the Judge Advocate General (JAG) corps who handled detainee abuse and friendly fire cases - and looks to precedent and the law to try to parse the question.

"If you look at the lease, freshwater pearl earrings it's America as long as we want it to be America," he says. "I'm not sure how that functionally is any different than Puerto Rico."

In 1965, he said, the U.S. declared the base a special maritime jurisdiction and brought a Cuban to federal court in Miami for the machete killing of another non-U.S. citizen on base. For that crime, Guantanamo was subject to the prosecutorial jurisdiction of the United States. Since the Bush administration chose to imprison war-on-terror captives seized across the globe, it has sought to make sure the opposite applies.

That's why moments before boarding a U.S. military charter to Guantanamo at Andrews Air Force Base - the place where the Pentagon parks the president's plane, Air Force One - an airman warned two Chinese journalists that going to Guantanamo would amount to entering a foreign country, Adon jewelry and their single-entry work visas would be invalid on their return.

They were invited by the Office of the U.S. Secretary of Defense to report on some war crimes hearings and were scheduled back a week later, on a nonstop flight.

They didn't go.