Men of action is not the same thing as men of acting, as this film about the Navy SEALs in the post-9/11 world makes clear. The producer-directors of the picture, Mike “Mouse” McCoy and Scott Waugh, appear in a brief prologue to discuss, among other things, their decision to employ active-duty (and unidentified) SEALs in the leads rather than actors; they argue that only by doing so could they capture the emotional range of the characters. That’s nonsense, of course, and an insult to the acting profession. And its inaccuracy is demonstrated in a scene the director points to—the one where the men bid goodbye to their families as they go on a dangerous mission. If this were a documentary capturing a real moment, the effect would certainly be powerful; but here, as the warriors, their wives and children try to replicate such an episode before the camera, the flat line readings and stiff performances undermine the impact. The defect is exacerbated by the writer Kurt Johnstad’s decision to employ narration throughout, a text filled with purple prose delivered in dull monotone by one of the men.

That means that all of the expository scenes in “Act of Valor” are really pretty bad. But the action ones have visceral energy, though even in this respect it falls short of a many war films that have choreographed their fighting scenes with greater clarity and precision. And the entirely fictional plot that’s been devised to showcase them has no subtlety whatever. It begins with a mission to rescue a captured female undercover agent who’s been investigating a shady arms dealer in Costa Rica. That involves a raid on a well-guarded jungle compound (though it’s never made clear how the location was ever determined), complete with firefights, car chases and some speeding gunboats and helicopters.

The success of that operation in turn leads to another, since intelligence derived from it discloses a plot by a fanatical terrorist (Jason Cottle), who’s already killed an American ambassador and a passel of children in a bomb attack, to infiltrate a slew of suicide bombers across the Mexican border into the US, where they will detonate vests equipped with undetectable plastic explosives in crowded areas. Working with Mexican police headed by a steely leader (Nestor Serrano), the SEALs first launch an assault on an island staging area off the coast and then a desperate effort to prevent the surviving terrorists from entering the States via tunnels—which also brings them up against the forces of a Mexican drug lord. The picture closes with a funeral eulogizing one of the men lost in the operation, followed by a list of SEALs actually killed in missions conducted since 9/11, to whom it’s dedicated.

Under these circumstances it might seem churlish to criticize, but unfortunately “Act of Valor” too often comes across as hackneyed and amateurish. The SEALs who play the leads are certainly convincing in the action sequences, but can’t carry the dialogue ones with any conviction. (To be fair, veteran actors would have trouble dealing with the cornball dialogue provided by Johnstad, a co-scripter of “300.”) And the professionals who are involved in other roles—like Roselyn Sanchez as the captured (and tortured) agent, or Alex Veadov and Cottle as the villains, or Serrano as the Mexican cop—don’t fare appreciably better. Veadov and Cottle, in particular, suffer from characterizations that make the bad-guy posturing of the nasties in such pulpy exercises as the “Die Hard” movies look positively multifaceted by comparison.

As emphasis on the use of Special Forces accelerates in today’s military, a tribute to the courage of the SEALs is certainly appropriate. And it must be said that “Act of Valor” is less meretricious than Louis Teague’s ludicrous 1990 movie about them, which enthusiastically embraced every Hollywood war-picture cliché of its time while finding Charlie Sheen giving what was probably his most embarrassing performance prior to his recent public meltdown. But this picture is actually no less cliché-ridden than that one, and as a film rather than an encomium, it leaves much to be desired.