The prologue of the Red Dawn remake is a whiplash-inducing montage of factual newscasts and fictional narration, suggesting America’s contracted economy has eroded efficient defense against tyrannical nations who may do more than rattle sabers.

The film enforces its own severe austerity measures — streamlining the paranoia, politics and pacing of the 1984 original for an aggressive, action-only approach.

Yes, Red Dawn thunders through 94 swift minutes, with a commanding central presence. Though he shot his role long before his fame as Thor, Chris Hemsworth offers his best-yet leading-man performance here. (Similarly, a pre-Hunger Games Josh Hutcherson shows up in a supporting role.) But next to its forerunner, it’s timid and toothless. Had it not gone gun-shy about the identity of its international enemy, today’s Red Dawn could’ve had bite.

Originally, China was to be the invasive force, collaborating with Russia. Imagine the potency of that narrative powder keg — America’s trillion-dollar creditor tossing out our debt in exchange for forcible occupation and societal reeducation, all under the eye of propaganda posters reading “Helping You Fight Corporate Corruption” and “Getting You Back On Your Feet.”

Instead, in one of many decisions that delayed Dawn (which finished filming nearly three years ago), China was replaced by North Korea, mainly via visual effects. This came after sharp Chinese criticism of leaked script excerpts and worries that this costly $75 million film might face boycotts in a crucial international market.

Like the original, Russia is really driving the bus here. But the intended endgame — or the victor-spoils terms brokered by these clearly inequitable powers — is unmentioned. As it stands, this Red Dawn means to trade not on current anxiety, but the bankability its stars acquired while the film languished on studio shelves.

It swaps small-town Colorado for big-city Spokane — which urbanizes and, in a subtle way, undercuts, the undertaking. Granted, Spokane isn’t a super-city, but the desolation of oppressive internment in middle-of-nowhere America never really sets in. The closest it comes is a hitch in the throat as Mayor Jenkins (Michael Beach) introduces Colonel Cho (Will Yun Lee) as “the acting prefect of this district.”

And this script consolidates characters and traits, namely in Hemsworth’s Jed Eckert. He’s now a Marine who makes an unexpected return home to see his policeman father (Brett Cullen) and Matt, a star-quarterback brother forever in Jed’s shadow, played by Josh Peck — whose dopey-droopy face looks nothing like Hemsworth whatsoever. (Fans anticipating one specific line from Cullen may feel cheated; instead, he says what a dad motivating sons to fight back might really say.)

In the original, Powers Boothe played a downed Air Force pilot whose field-tested fighting style helped whip a group of displaced teenagers into a mighty militia. A variation on that character, played by Boothe lookalike Jeffrey Dean Morgan, eventually shows up. But it’s now Jed who assumes the lead after the battle begins.

Said invasion steals a page from Jurassic Park before a frisson of fury, with hellacious explosions and concussive, cage-rattling camerawork on which first-time director Dan Bradley (a second-unit man on the latter Bourne films) has made his name.

But it lacks the insidious, iconoclastic shattering of American peace seen when a lone paratrooper executed a high school history teacher in the original. Here, enemies descend in immaculate, digitized formations. And when a North Korean squad has the drop on the Eckert boys, they stand like statues with their assault rifles.

Instead, Jed and Matt escape to their family’s isolated forest cabin, along with Robert (Hutcherson), Toni (Adrianne Palicki of TV’s Friday Night Lights) and Daryl, the mayor’s son (Connor Cruise, the adopted son of Tom Cruise and Nicole Kidman).

Only in Cruise’s hands does a gun ever feel disquietingly larger than the child holding it, and he plays it to understated, ultimately mournful effect. Only 14 when Red Dawn was filmed, Cruise has clearly heeded his parents’ best advice.

Joining them are Danny (Edwin Hodge), Julie (Alyssa Diaz) and Greg (Julian Alcaraz), whose names might as well be Expendable Ethnicities 1, 2 and 3. While the remake admirably diversifies the group, it also plays right into every imaginable stereotype.

You may also expect their coalescence into a guerrilla unit known as the Wolverines to be a bit more cautious and not altogether confident. But the movie dispenses with their armament, and training, in a slick montage. This swift passage of time is a shift from the spirit-sapping seasonal changes of the original, omitting a sense of just how long these kids are out there fighting.

Thankfully, Dawn slows for Hemsworth to put forth moments of convincing conflict and stillness, as striking as they are in short supply. Jed fled a family fractured by a mother’s death into the arms of the Armed Forces — his life forever defined by the young-adult impulse he’s trying to corral in those under his charge.

“These things are badass,” Robert says of a fully automatic handgun. “Not if you know anything,” Jed barks back — a wounded warrior, not a “cold, dead hand” guy.

Jed also astutely observes some townspeople’s capitulation as a different choice than he has made, not a shifted loyalty. And he notes no one’s suffering is unique, least of all Matt’s, who unwillingly left behind his girlfriend, Erica (Isabel Lucas). Matt’s insistence on liberating Erica threatens to undermine the carefully choreographed attacks that could thwart, and unseat, Cho and his cohorts.

Bradley and his team bring crisp professionalism and panache to all of the action sequences, which culminate in a Marine-assisted raid to secure a North Korean secret weapon. He’s hindered only by occasionally going overboard on cut-rate CG and a bizarrely abrupt ending that opportunistically, and unadvisedly, leaves the door open for more.

Essentially, it’s a technically proficient, matinee timewaster — not the palpable, clammy-palmed geopolitical nightmare that could have been.