If the picture is shaky and disorienting, then either the projectionist is having problems or you’re watching a film by Paul Greengrass.

His signature “faux cinéma vérité” style is designed to give his movies a more realistic, documentary-like feel. It’s a method he’s used successfully in movies like “United 93,” “Bloody Sunday” and the last two “Bourne” films.

He applies this method to his latest effort, “Green Zone,” a fictitious Iraq war thriller “inspired by” the non-fiction book “Imperial Life in the Emerald City” by Washington Post journalist Rajiv Chandrasekaran.

“Green Zone” is actually a political commentary disguised as an action flick, pointing a defiant finger at the Bush Adminstration.

In the early days of the American invasion of Iraq, Chief Warrant Officer Roy Miller (Matt Damon from “The Informant!”) and his squad are searching for weapons of mass destruction. Although he continues to receive specific location info from the intelligence community, he keeps coming up empty.

Could someone be lying?

Ultimately, Roy becomes something or a rogue agent. He joins forces with Martin Brown, the Baghdad CIA bureau chief (Brendan Gleeson from “In Bruges”), to find Saddam Hussein’s general who, reportedly, knows about the nukes.

But the Pentagon Intelligence honcho in Baghdad, Clark Poundstone (Greg Kinnear from “Ghost Town”), doesn’t want the Baathist general take alive. Is it possible that Poundstone knows that there AREN’T any WMDs and doesn’t want the general to blow the whistle?

Further complicating matters is a Wall Street Journal reporter named Lawrie Dayne (Amy Ryan from “Gone Baby, Gone”) who has been writing regularly about Iraq’s active WMD program. She’s been getting her info from Poundstone.

While this all sounds like a political shell game, Greengrass and screenwriter Brian Helgeland (“Mystic River”) set it as a breathless action flick. Most of Damon’s screen time is spent running, shooting and getting beaten up.

Spain, Morocco and the UK substitute beautifully for Iraq. Cinematographer Barry Ackroyd (“The Hurt Locker”) and the movie’s special effects wizards work together seamlessly to create an authentic-looking war zone.

Ackroyd follows Greengrass’ lead, moving his camera at a dizzying rate and employing ambient low light to give the image the kind of grainy look that an imbedded photojournalist might capture.

A little of this herky-jerky cinematography goes a long way. Many audience members will undoubtedly become disoriented and frustrated with the constant camera movement. Plus, the level of diminishing returns is often reached when there is no break in the action.

Yet, “Green Zone” remains compelling. Anyone familiar with the cluster that occurred in the first few months of the invasion will recognize the Poundstone and Dayne characters as thinly disguised versions of Paul Bremer and Judith Miller.

While it’s preachy and not always credible, “Green Zone” remains a compelling, intriguing and intense war drama. (R) Rating: ***1/2

* Avoid at all costs
** Only if you're bored
*** Good movie
**** Well worth your time
***** Be sure to see it