The success of ballistic missile defences facing their first complex, high-stakes combat scenarios in Israel, the Red Sea and Ukraine will encourage militaries globally to invest in the pricey systems, experts say - and intensify missile arms races.
Iran launched as many as 120 intermediate-range ballistic missiles at Israel on April 13, US and Israeli officials say. US SM-3 and Israeli Arrow interceptors destroyed nearly all of them, leaving drones and smaller threats to the Iron Dome system.
In previous months, interceptors fired from US Navy destroyers stopped Houthi anti-ship ballistic missiles, while in Ukraine, US-made MIM-104 Patriot batteries have shot down advanced Russian Iskander and Khinzal missiles.
Reuters spoke with six experts who said more militaries would look to invest in ballistic missile defence, a potential windfall for companies such as Lockheed Martin and Raytheon, which build those types of systems.
"It's undeniable that any wealthy country with the technological wherewithal will continue to invest in missile defence," said Ankit Panda of the US-based Carnegie Endowment for International Peace, a defence and security think tank. "All of this is a recipe for a conventional arms race."
European countries such as the Netherlands, Germany, Sweden and Poland already operate RTX subsidiary Raytheon's Patriot batteries, the most common Western advanced ballistic missile defence system.
Saudi Arabia has used its Patriots for years to defend against Houthi attacks; it and the United Arab Emirates also operate the Lockheed Martin Terminal High Altitude Air Defense (THAAD) system. Kuwait, Qatar and Bahrain have Patriot batteries as well, and Oman has expressed interest in missile defence.
In the US, Lockheed Martin in April won a $17.7 billion contract for a next-generation interceptor for the Ground-Based Midcourse Defense (GMD) program - designed to shoot down small numbers of intercontinental ballistic missiles (ICBMs) aimed at the continental United States.
But the impact may be most acute in Asia, where China has invested heavily in conventionally armed ballistic missiles. A 2023 Pentagon report said the People's Liberation Army Rocket Force has about 500 DF-26 missiles, designed to accurately strike targets thousands of kilometres away.
That puts US and allied bases in Japan and Guam within range of an attack that may only come with 20 to 30 minutes' warning.
"In the Pacific, you’ll see further interest in missile defence, which will push the Chinese to build more systems," said Jeffrey Lewis, director of the East Asia Nonproliferation Program at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies in California. "Countries will want to acquire (offensive) missiles because they see other countries using them ... That will drive up demand for missile defences."
US Indo-Pacific Command and China's Ministry of Defence did not respond to requests for comment.
China rarely discusses its missile arsenal beyond statements that its forces are meant to preserve peace and are not aimed at any specific country.
Raytheon did not respond to a request for comment. A Lockheed Martin spokesperson referred questions to the company's first-quarter earnings briefing in late April, in which it said it continued to lead the industry in "missile defence missions, which, given world events, are becoming more critical than ever".
Dollar signs
Ballistic missile defence works by spotting an attacking weapon either at launch or in flight, then using a surface-based radar to guide an interceptor to the target.
Interceptions can occur in the atmosphere or in space, and each domain requires different hardware. For instance, fins won't work outside the atmosphere - interceptors must have small steering rockets to function there.
The necessary high-powered computers, far-seeing radars and missiles as large as telephone poles are not cheap, together stretching into the billions. In 2022, for example, the US approved the sale of both Patriots and THAAD systems to Saudi Arabia, in deals worth as much as $5.3 billion.
In the Indo-Pacific region, wealthier countries such as Japan, Australia and South Korea are prime candidates for missile defence, Lewis said, while nearly every country in Asia is already investing in missiles.
Japan's defence ministry said the country "needs to fundamentally and swiftly reinforce its defence capabilities, including integrated air and missile defence". It said it is investing in improved Patriot missiles, better radars and enhanced naval anti-missile capabilities.
In its latest defence budget, South Korea increased funding by 12% for its Korea Air and Missile Defense System to expand it "from the existing lower-level defence concept," the country's defence ministry said in a statement.
"Cases such as the Israel-Hamas conflict and the Russia-Ukraine war have reaffirmed the importance of a 'ballistic missile defence system' to respond to increasingly sophisticated missile threats," the ministry said.
In mid-April, Australia announced a A$500 million ($328 million) contract with Lockheed Martin to deliver its Joint Air Battle Management System for tracking and destroying aircraft and missiles.
The cost of a ballistic missile is often much cheaper than the system meant to stop it.
But that isn't the right way to consider cost, said Yoji Koda, former commander in chief of Japan's Self-Defense Fleet, and an advocate of stronger missile defences in his country.
"In a war economy, the cheaper the better. But sometimes what is necessary, is we need to protect key infrastructure, or key command centres, at any cost. Because without them we would lose."
The China question
Most of China's conventionally armed ballistic missiles are designed to hit targets on land.
But it also fields steerable warheads meant to hit ships at sea, including the DF-21D and variants of the DF-26, developed by the state-owned China Aerospace Science and Technology Corporation.
Such anti-ship ballistic missiles (ASBMs) had never been used in combat until late 2023, when Houthi forces in Yemen began firing Iranian-made models at ships in the Red Sea.
Between November - the first documented use - and April, US Central Command reported at least 85 ASBMs fired in the region, with 20 interceptions and one civilian ship reported sunk.
CENTCOM has declined to provide specifics about the effectiveness of Iranian ASBMs but has noted missiles posing no threat were not engaged and most that were not intercepted landed harmlessly.
The effectiveness of missile defences on land and at sea will catch China's attention, said Tong Zhao, a senior fellow with the Nuclear Policy Program and Carnegie China.
"It raises the possibility that the US and its allies could depend on missile defence significantly against a ballistic missile attack," Zhao said.
Although the technical specifics of China's missiles are closely held secrets, the country's heavy investment means they are likely to be more reliable, and are widely believed to use complex countermeasures to complicate interception.
"For opponents such as China which have missile stockpiles an order of magnitude larger than that of Russia or Iran and which field more sophisticated systems ... it's not clear that the lessons learned invalidate existing operational constructs," said Sidarth Kaushal, a senior research fellow at the Royal United Services Institute.
But the political and practical incentives to invest in missile defence will be too attractive for many countries to ignore, Lewis said.
"All defence procurement decisions are ultimately about politics," he said. "The politics of this stuff is really simple: do you want to defend the country or not? And the winning answer is always 'Yes'."