It’s been a tough road for the F-35 Joint Strike Fighter, the next generation fighter jet running years behind schedule and billions over budget. But, the Air Force says, better late and crazy expensive than never. In its first serious test, the F-35 proved that given the chance, it can wreak havoc in the skies.

That test was Red Flag, the Air Force’s annual, weeks-long, all-hands-on-deck, multinational shakedown of military aviation technology. In the skies over the Nevada desert, drones run recon drills. Electronic-warfare planes jam signals and hunt enemies. Cargo aircraft move crews and supplies in and out of Nellis Air Force Base, outside Las Vegas. Fighter jets on the “blue” team face off against the “Red” forces—specially trained aggressor squadrons that mimic the real-world tactics of US adversaries.

Over 110 sorties, the fleet of 13 F-35A jets (the Air Force-dedicated version of the fighter) posted a simulated kill ratio of 15:1, according to Aviation Week, meaning only one blue aircraft was shot down for every 15 reds the F-35 threw to the ground.

The sadists running the drill went hard after the newcomer, using advanced tactics and targeting and jamming technologies, and deploying extra “enemy” F-16s (in adversary-appropriate camouflage). No match, apparently, for the plane’s advanced data-gathering and sensing technologies (like a $400,000 helmet). That didn’t just boost the airmen in the F-35s—pilots flying F-22 Raptors and older F-18s and F-16s enjoyed improved situational awareness, too. Defense News reported that the F-35s stuck around after unloading all their weapons, so other aircraft could crib data from their scanners.

The success in the mock combat may not assuage President Trump’s concerns over blown budgets and deadlines. “There are many sighs of relief,” says military analyst Peter Singer. “But the challenge for F-35 has always been something else that won’t be able to change all that much—its costs and, maybe more so, the opportunity costs of what could be bought instead.” In other words: The fact that this thing works doesn’t mean all is forgiven.

Even if it had flunked Red Flag, the plane would have lived on, Singer says, because it has safely reached "too big to fail" territory. The question now is how a manned jet born of the 1990s will age in a world of ever smarter, autonomous uncrewed alternatives, and what the competition puts in the air. China and Russia are building comparable jets, and working on sensors designed to track jets like the F-35.

The Red Flag success suggests the fighter, which has been fairly accused of being overcomplicated, can keep pace with what some see as simpler, more robust systems like the F-18. “This is an aircraft that depends heavily on things working—sensor data links, weapons systems, etc,” says military analyst Richard Aboulafia. “The simulation didn’t prove that it’s the ultimate dogfighter or has the most powerful missiles, far from it. But it proved that when everything is working it’s a formidable system.”

For now, the debate seems settled in favor of the F-35. Here’s hoping that conversation stays academic.