Inasmuch as there could ever be a good time to premiere a film about the 2011 Utøya massacre, “U – July 22” arrives at a particularly tender, difficult moment. Unspooling at the Berlin Film Festival five days after the Parkland mass shooting in Florida, Erik Poppe’s appropriately agonizing single-take reconstruction of the right-wing terrorist attack that left 69 dead at a political youth camp on a Norwegian island will prompt particularly heated debate as to the ethics and ultimate value of recreating contemporary tragedy as an exercise in cinematic tension. There’s little arguing with the technical agility and brute impact of Poppe’s film, however, which also makes the prudent choice of maintaining the victims’ perspective — fictionalized, but drawn from survivors’ accounts — to the end, while the shooter, Anders Behring Breivik, is barely glimpsed on screen.

If “U – July 22” avoids some of the grisliest pitfalls of such dramatization, however, those concessions won’t settle the more complicated question of whether or not it needs to exist at all. It may teach us nothing about the events of July 22, 2011 that we didn’t already know — save, perhaps, for a more heart-stoppingly tactile impression of what it might have been like to be caught in the maelstrom for nearly 90 nightmarish minutes. There is an argument to be made for its status as a kind of operational in-memoriam monument: a flat reminder of what happened, lest too many subsequent shootings make prospective viewers forget this one’s appalling specifics, rendered in digital stock rather than bronze. However the debate proceeds, the film remains an awfully challenging sell internationally, though festival programmers will continue to stoke the fire.

Fully aware that it’s walking on eggshells merely by taking on this material in the first place, “U – July 22” includes not one but two disclaimers in its closing credits. The first clarifies that all its characters are the invented creations of screenwriters Siv Rajendram Eliassen and Anna Bache-Wiig; the second defends its screenplay’s fact-rooted fabrication by admitting, “Its basis is one truth — others may exist.”

Indeed, in filtering the events at hand through the imagined experience of 18-year-old Kaja (a formidable Andrea Berntzen, who has something of the doughty teenage Jennifer Lawrence about her), Poppe and the writers have personalized and narrativized the Utøya tragedy to make it emotionally compelling to viewers. Though few would describe the resulting film as “entertainment,” the selection of a heroine — a conscientious leader type doing her best to stay alive while looking out for others — to root for amid the chaos, and the clicking conduction of suspense as to her fate, are subjective ploys that won’t sit well with viewers who approach “U – July 22” seeking a longer view.

In the moment, the film’s manipulations are effective at a heart-in-mouth level. The isolating arm’s-length formalism of Gus van Sant’s “Elephant” is emphatically not the approach Poppe (best known for such glossy, audience-friendly pictures as “A Thousand Times Good Night” and “The King’s Choice”) has taken here. Nor is anything approaching documentary technique — save for dialogue-free, CCTV-style footage at the film’s outset detailing the car bomb explosion in central Oslo, also executed by Breivik, that preceded the shootings by just two hours, killing eight. Cut to the remote, idyllic island of Utøya, where news of the attack is slowly trickling through to 500 teenagers gathered for a summer camp run by the left-wing Workers’ Youth League — stuttered and staggered by a faint cellphone signal.

Working from the start with a roving camera, propulsively steered by Martin Otterbeck, Poppe sticks close to popular, responsible Kaja as she absorbs the tragedy and lightly admonishes her more fun-loving younger sister Emilie (Elli Rhiannon Müller Osborne) for showing insufficient solemnity in the circumstances. Mere minutes pass before the first gunshots are heard in the distance, and fevered, uncomprehending panic ensues. Though Kaja initially makes a run for it with a group of friends, her needling concern for the missing Emilie spurs her to go it alone, like a horror film’s final girl — bolting for her life across the campsite, the surrounding woodland and finally the island’s crevice-laden shore as regular gunfire dully rings in her ears. (Bullets practically serve as a score in Gisle Tveito’s disorienting, multi-directional sound design.)

With the entire ordeal staged, like Sebastian Schipper’s recent “Victoria,” in an exacting, significantly ground-covering single shot, “U – July 22” is designed to be as immersive as it is exhausting, and largely succeeds — though it lumps in some moments of sticky contrivance, as when Kaja sings a bell-clear, a capella rendition of Cyndi Lauper’s “True Colors” to comfort her fellow victims as they await their fate. It’s only once proceedings finally, mercifully cut to black that the moral conundrum of the whole enterprise kicks back in: Does “U – July 22” finally leave its audience with anything? How could it, given the numbing senselessness of what it depicts? Perhaps that’s the very point of Poppe’s film; it’s for the individual viewer to decide if that emptiness is enough.