For the hardware at the pointy end where battles are won or lost, no. For example, the 737 uses high bypass turbofans optimized around fuel burn, the fighter h

For the hardware at the pointy end where battles are won or lost, no. For example, the 737 uses high bypass turbofans optimized around fuel burn, the fighter has a low bypass afterburning turbofan optimized around weight. Huge divergence. (And by the way, on both the civilian and military sides, engine development programs are yuuuge and very long. There's a reason for that that isn't simply due to greed.) The 737 has a standard weather radar, the fighter is able to focus megawatts in a narrow arc across less than a square centimeter of its nosecone and employs all sorts of trickery to resist (and possibly inflict) jamming, while detecting small targets that are trying to evade by blending into ground clutter or disappearing into something called the Doppler notch. Another huge divergence. Meanwhile the entire aircraft has been designed with stealth in mind, and that's a skill set with no civilian counterpart -- when was the last time you heard of an electrical engineer calling the shots on airframe design? Even designing for high supersonic aerodynamic performance (maneuvering, not just cruising) is pretty much a military-only skill, and supersonic analysis is wildly different from its subsonic equivalent. It just goes on and on -- I haven't even brought up guided missiles, which result from substantial development programs of their own and benefit little from civilian technology. Now, there might be some subset of military products for which there aren't as many valuable differentiators -- I'm thinking of things like logistics assets, vehicles and infrastructure designed to move war materiel where it's needed. And there's precedent for that, where for example civilian airliners are converted into tankers. But on the whole, you can't take what you've learned building a 737 and apply that to building a competitive jet fighter inside of any reasonable time scale. So, could you go to war with a 737 and a bunch of bombs hanging off it? Against insurgents, probably, yeah. But it's going to cost a lot more than, say, an A-10, the ground troops won't get any guns passes from you, and a single Su-27 is still going to ruin your whole day. Another attractive option might be to skip a generation of hardware. But an important thing to remember is that every time a wise head retires from military aerospace, valuable skills and knowledge are lost. Sure, things are documented, but you can't easily replace human know how. So what happens when you go 20 years without a major fighter program? Experienced hands get thin on the ground and you spend a good amount of time and money climbing out of that hole. The upshot is that even if you'd like to get off the military upgrade treadmill for a while, you're going to pay some significant fraction of that savings down the road, whether in increased cost, schedule and/or reduced product performance. Having said all this, I believe there are better ways to do what we're doing, and I think the F-35 was a foundationally ill-conceived program. But hand-picking a few basic military technologies to nurse while leaving the rest to whatever the civilian market will support is not the way to fix it.