Battle: Los Angeles is a standard-issue combat film with a twist: The enemy is a hater from another planet. Camouflaged as meteor showers, armored aliens invade Earth to suck dry its natural resources.

Who you gonna call? The Marines, of course.

The filmmakers strictly observe the movie law that just as he's mothballing his uniform, a short-timer gets redeployed.

On the very day that he completes the paperwork for retirement, Staff Sgt. Michael Nantz (Aaron Eckhardt), still mourning the loss of men in Afghanistan, is in a platoon helicoptered into the City of Angels to reclaim Santa Monica from interplanetary devils attacking port cities around the globe.

His unit is peopled by the usual prospects. There's the corporal (Ne-Yo) about to get married, the private (Noel Fisher) who's never been in a battle or with a woman, and the second lieutenant (Ramon Rodriguez) untested in combat and an expectant father. Naturally, one of the men in the platoon (Cory Hardrict) is the brother of one of the leathernecks that Nantz lost.

Thus, Nantz has to battle the aliens while fighting for the platoon's respect and coaching the second lieutenant.

The mission seems as simple as a video-game objective: Rescue civilians stranded at a police station and bring them back to base before the U.S. bombs Santa Monica to sweep the coast of these seemingly invincible invaders.

(If the geography looks not at all like Los Angeles, that's because director Jonathan Liebesman shot it in Louisiana.)

But the enemy is much cannier about disabling Earth's weapons than vice versa.

As a narrative, the cartoonish Battle: Los Angeles makes the cartoonish Independence Day look as nuanced as Saving Private Ryan. It works as a film diversion because of Eckhardt's unwaveringly earnest and resolute performance. Her fans (I am one) will cheer the presence of Michelle Rodriguez, perhaps the only Hollywood actress who looks plausible in military uniform.

It is a little too slippery to work as an allegory. Are we to take it that the aliens represent earthlings who colonize the Middle East and Africa in order to make off with the regions' natural resources? That this is a cautionary tale about any people who would wage war in order to win the spoils of oil and water? Your guess is as good as mine.