Total air defense is effectively impossible. In a major war, the West may have to make hard choices.

The West has strong air defense systems, but would still have to make choices about where to protect in a large-scale war. Sean Gallup/Getty Images 2026-03-26T09:30:01.261Z Share Copy link Email Facebook WhatsApp X LinkedIn Bluesky Threads lighning bolt icon An icon in the shape of a lightning bolt.

Impact Link Save Saved Read in app This story is available exclusively to Business Insider subscribers. Become an Insider and start reading now. Have an account? Log in. Air defense is becoming harder than ever in modern war with drone and missile proliferation. It makes it effectively impossible to defend everything — even with substantial spending on defenses. In a major war, the West would have to make tough choices about what to protect. AI-generated summary Summaries are generated by an AI model trained on Business Insider's articles. AI may make mistakes or provide inaccurate/incomplete information. We're unable to load that answer right now. Please try again. How do drones complicate air defense? How does missile proliferation impact war? How can countries prioritize defense targets? What factors influence defense priorities? What is a "wicked problem set" in defense? In a major armed conflict, even the most advanced militaries will not be able to stop all incoming attacks everywhere, forcing them to decide what they're willing to lose, a hard choice. Loading audio narration... The wars in Ukraine and the Middle East are previewing possibilities for future fights as mass drone attacks stack on top of missiles in heavy ranged bombardments.Russia's invasion of Ukraine has shown that targets in a large-scale war may not be military alone. They may be residential areas, schools, hospitals, and energy infrastructure. It's not possible for a country to cover everything with its air defenses, experts said. Ukraine, even with some of the most capable layered air defenses, still gets hit regularly — showing that "you can never protect everything," Justin Bronk, a top airpower expert at the UK's Royal United Services Institute, told Business Insider.Similar challenges have emerged in the US-Israeli war against Iran. US Defense Secretary Pete Hegseth said earlier this month that possessing robust air defenses "does not mean we can stop everything." Every time Sinéad publishes a story, you'll get an alert straight to your inbox! Stay connected to Sinéad and get more of their work as it publishes. Sign up By clicking "Sign up", you agree to receive emails from Business Insider. In addition, you accept Insider's Terms of Service and Privacy Policy. Bronk said efforts in the West to build vast protective shields are "misguided" because "it's completely impossible to defend everything." There are limitations in systems, money, and people.Trying to defend all of Europe from Russian strikes, for example, would use "the entire European military budget and more." It's not tenable — and you can't win a war just by defending. Defenses have to be prioritized. "You've got to make tough choices," former Australian Army Maj. Gen. Mick Ryan said.New threats are complicating air defenseAir defense has always been harder and more expensive than attack, and the threat environment is only becoming more complex. "Some things will get through," Mattias Eken, a missile defense expert at RAND, told Business Insider.Stopping every incoming missile in a large-scale attack is effectively impossible. Building full-coverage missile defense, said former Finnish defense chief Jarmo Lindberg, is "the most expensive thing, probably, on the planet." Now drones are compounding the problem, threatening far more targets at a fraction of the cost. Russian drones have created a host of new attacks for Ukraine to stop, just as Ukrainian ones have for Russia.

Russian Defense Ministry / Handout/Anadolu via Getty Images Salvos can include dozens of drones at once. Even outside war, drones have disrupted airports, cities, and military bases across the US and Europe. Douglas Barrie, an air power expert at IISS, said air defense has gotten "more difficult" as ballistic missiles have proliferated, combat aircraft remain, and now there are huge masses of drones to stop, too. "It's a wicked problem set that's coming home."Ukraine shows what this looks like in practice. It fields a mix of Soviet-era systems, Western-donated defenses, and domestic solutions to protect both cities and military targets, yet "they still get hit all the time," Bronk said. Ukraine has to make choices on its defense as it faces ballistic and cruise missiles, drones, and glide bombs, among other threats. Tough decisions to makeEven if Ukraine had twice as many US-made advanced Patriot air defense systems, Ryan said, "it would still need to make really hard choices about what the priorities to protect were."In a wider war, those tradeoffs could scale across Europe. Ukraine's experience, Barrie said, shows that in such a conflict "Europe will inevitably have to make difficult choices." Countries will need to identify what must be shielded, what they'd like to protect, and things that are simply going to be left undefended. Ukraine has not been able to stop all of Russia's drone and missile attacks. Viktoriia Yakymenko/Suspilne Ukraine/JSC "UA:PBC"/Global Images Ukraine via Getty Images A former Western air force intelligence officer who spoke to Business Insider on the condition of anonymity to discuss warfighting lessons said Ukraine is being forced into constant tradeoffs and "difficult decisions," an big one being: do you move air defenses forward to protect troops or hold them back to defend cities?During the Cold War, Western defenses prioritized nuclear forces to preserve deterrence — not cities, which were understood to be largely indefensible in full-scale war. "You can't throw enough at air defense to defend everything from everything," Bronk said.Air defense is still essentialThat said, air defense capacity in the West is still deeply insufficient for a large-scale war or a protracted campaign. NATO lacks the necessary ground-based air defenses and is rushing to buy more, but systems take years to produce, face backlogs, and are expensive. Cheap drone interceptors, which Ukraine is fielding at scale, are emerging but haven't yet spread widely across the alliance. Allies are now scrambling to buy them, with limited supply. Ukrainian companies have developed interceptor drones that soldiers are using to down Russian drones at a low cost. Genya SAVILOV / AFP via Getty Images Even with these tools operating alongside traditional air defense systems, stopping every attack is unlikely. "Is it possible to provide very, very good counter-drone protection for specific protected areas or objects? Yes. Is it possible to protect everywhere like that? No," Bronk said.Drones can approach from multiple directions against a huge range of targets. Something will always be exposed. Agris Kipurs, the CEO of Latvia-based firm Origin Robotics, which makes low-cost interceptor drones, said that trying to stop everything is a daunting challenge. It's been a struggle, he said, and "it still is and probably will continue to be.""Stopping absolutely everything is very complicated," he said. "With the number of threats growing, the challenge grows as well."