So, the apocalypse seems to be drawing nigh, but what are the details?

As it turns out, while CNN was showcasing fundamentalist Christian authors hawking books about the “end of days,” the Pentagon was imagining a scenario that looked awfully close to the real thing.

In mid-April, Defense Department futurists gathered in Hawaii for a war game that started with Iranian attacks on Persian Gulf shipping, particularly oil tankers.

The U.S. Navy, according to the scenario, sailed to the rescue through the Straits of Hormuz. China decided it’s a good time to invade Taiwan.

With missiles — possibly nuclear — flying there, Venezuela’s populist leader Hugo Chavez, acting in concert with Beijing, dispatches submarines against U.S. oil and gas rigs in the Gulf of Mexico and coastal refineries in Louisiana and Texas.

Pretty funny, huh? Especially the part about Venezuelan submarines. Some other key elements of the war game don’t much makes sense, either, such as China, Washington’s major trading partner, throwing it all away for Taiwan. Not likely — for now.

But if history teaches us anything, it’s that nightmares, not just dreams, can come true. Witness Japan’s suicidal attack on the United States in 1941, or Russia putting nuclear missiles in Cuba in 1962.

And now, with the Hezbollah-Israel conflict burning toward Syria, the Pentagon war gamers’ doomsday needle seems to be ticking from improbable to possible.

Why? Because the battle for Lebanon arguably presents the greatest potential for spinning into a global conflict in over 30 years.

Iran has a lot at stake in the survival of its Shi’a protege, the Hezbollah fighters who have proved surprisingly resilient against superior Israeli forces in Lebanon. The only reason Hezbollah is having any success at all against Israel is because of the rockets and missiles Iran gave it.

A stalemate in southern Lebanon means that revolutionary Iran has established an even bigger footprint in the region, flanking U.S. forces in Iraq.

Influential U.S. conservatives have been calling for an attack on Iran before it develops a nuclear bomb, or at the very minimum “regime change.”

Iran’s President Mahmoud Ahmadinejad has promised he won’t sit on his hands in the face of U.S. provocation.

Meanwhile — and this is where the war game meets a chilling reality — both President Bush and his Iranian opposite believe in their own version of the “end of days” and mass “raptures.”

Religious psychosis driving the crisis? It’s on a lot of minds.

Or as CNN anchor Kyra Phillips put it, introducing the rapture-me-now Christian authors again last week: “So . . . the buzz is all about the end times.” (At the bottom of the screen: “Apocalypse Now?”)

“Well, that’s what’s on my mind these days as well,” says Zeyno Baran, director of the Hudson Institute’s Center for Eurasian Policy.

“I think with Bush and Ahmadinejad both thinking history will prove them right, and both believing God is on their side and they are the ones to bring ‘freedom and stability’ to the Middle East and the world, we are moving fast to a major chaos in the Middle East.”

“I see the Lebanon case as the prelude to an attack on Iran,” Baran continued, “either by Israel or the U.S. And that would of course unleash all kinds of suicide bombings and small and large scale terror incidents anywhere and everywhere there are ‘soft’ American targets.”

Ahmadinejad has said as much, warning Bush against an air assault on his nuclear facilities. He faces a deadline of Aug. 31 to stop his nuclear program or face economic and political sanctions.

The Pentagon war gamers predict pretty much what Ahmadinejad has threatened.

His ports are bristling with fast-moving torpedo gun boats that he could throw at ships in the Gulf, bottling up the Straits of Hormuz like the Washington Beltway on a Friday afternoon, as the gamers predicted. He can also deploy terrorists from Iran’s embassies around the world, as he has against Buenos Ares in the past.

Who’s the dog that hasn’t barked here? Al Qaeda, whose star is fading as the plucky Hezbollah fighters in Lebanon draw raves from around the Muslim world.

According to some theorists, Osama bin Laden may feel he needs to get back in the game by launching a terrorist spectacular — perhaps against us here.

(A senior FBI source tells me “no movement” has been detected in the U.S. since the crisis began.)

Primacy in the Muslim world is at stake. Al Qaeda, along with its Saudi financiers, is Sunni; Hezbollah and its Iranians sponsors, Shi'a. The Sunnis and Shi’a have been fighting each other for 1,400 years, far longer than Catholics and Protestants in Ireland.

But think about this: Superpower primacy is at stake in the war game, too, as China, watching the U.S rush warships to the Gulf to protect shipping, decides the time is ripe to invade Taiwan. Bejing could decide it is time to bring the curtain down on the American Century.

Former Defense Secretary Bill Cohen, who has his own apocalyptic scenario arriving in book stores this month, says it’s “not probable.”

On the other hand, he quickly added, it’s “not impossible.

“You can spin out various scenarios that could lead to war. For example, if Israel were to expand its determination to eliminate Hezbollah and conclude that the only way to do so would be to attack Syria and Iran joins in defending Syria, well . . . .

“Or if Israel were to attack Iran directly, not only for its support of Hezbollah but also for moving forward in building nuclear weapons, then the improbability of a major regional war becomes an inevitability, which opens the door for multiple nations to be drawn into the conflict.”

If that weren’t enough, Cohen’s novel, called “Dragon Fire,” adds a dollop of right-wing militias stirring up trouble in the U.S. heartland over Mexican illegals.

Not to worry.

The U.S. built a pipeline across Saudi Arabia just for such an occasion, Cohen and other big thinkers point out.

They say the U.S. can handle all this.

Says the Federation of American Scientists’ Hans Kristenson, author of “U.S. Nuclear Weapons In Europe” and countless other heavyweight reports, “Iran has too much to lose in a region where they want to be the big counterweight to the U.S.”

“Besides,” he soothes, “a direct military conflict with Iran would not be WW III, no matter how we stretch it.

“Russia is not interested, and it’s not China’s style to get involved in distant wars or take advantage of them. If that was their style, they would have taken advantage of Iraq/Afghanistan long ago.”

But then again, he does have his worries.

“I think a direct confrontation with Iran is much more likely if they get into a fight with Saudi Arabia. That would be about territory and control of the Gulf.”

And so on.

Have a nice summer.

Jeff Stein can be reached at jstein@cq.com.