Written down somewhere, I swear, in the halls of Hollywood has got to be a directive decreeing that “action movies must end with a punch-out.”

It makes no difference how much artillery is employed in the early going. At the finale, hero and villain(s) must — I repeat: must — ditch the hardware and go knuckles to nostrils and elbows to Adam’s apples — Biff! Zok! — until everyone is a gooey, gory mess.

Two recent examples: “Gangster Squad,” featuring Josh Brolin pounding the stuffings out of Sean Penn, and “The Last Stand,” featuring Arnold Schwarzenegger whaling on some evildoing dude.

And now there’s “Olympus Has Fallen.” Director Antoine (“Training Day”) Fuqua’s tale of North Korean terrorists attacking and taking over the White House has lots and lots of weaponry. Handguns. Heavy machine guns. Super-duper airborne machine guns. Also fighter jets. Even nukes are worked into the mix. Small wonder the poor old White House is reduced to smoking rubble, walls riddled with bullet holes, columns spattered with blood, corridors strewn with corpses.

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But at the end, sure enough, there’s Gerard Butler, playing a heroic Secret Service agent, and Rick Yune, a dastardly North Korean terrorist mastermind, going all mixed martial arts on each other. Guns? Who needs ’em? Biff! Zok!

The picture is basically a ground-based version of “Air Force One” with a much higher body count. Instead of Harrison Ford, it’s got Aaron Eckhart serving as president/hostage/punching bag down in the White House bunker. Only Butler’s character can save him.

The action scenes are impressively staged. The audience absolutely gets the maximum amount of bang for their bucks. (Too bad about the Washington Monument.)

But what’s more interesting, and handled in a throwaway manner, is the picture’s politics. “The United States of America doesn’t negotiate with terrorists,” the captive president declares. Except, then he and the speaker of the House/acting president (Morgan Freeman) do exactly that, and in a hugely consequential way. It’s eventually all glossed over en route to the expected rah-rah ending, but along with people, high principles sure take a beating in “Olympus.”

Soren Andersen: asoren7575@yahoo.com