• A Houthi surface-to-air missile reportedly forced a US F-35 to take evasive action.
• The highly advanced F-35 is considered one of the top stealth fighter jets in the world.
• The aircraft, however, is not invisible or invincible.

What does it mean for a jet to be a "stealth fighter?" It means it's hard to detect and tough to strike, but it doesn't mean the jet is invisible or invulnerable.

The Lockheed Martin F-35 Lightning II Joint Strike Fighter, a top US stealth fighter, has been flying combat missions against the Iran-backed Houthi rebels in Yemen. During an intense two-month bombing campaign, both US Air Force F-35As and Navy F-35Cs were in the Middle East.

This week, multiple news reports citing anonymous US officials indicated an F-35 took evasive action during Operation Rough Rider to avoid being struck by a Houthi surface-to-air missile.

It's unclear if the F-35 was the target or to what extent the fighter was at risk. Neither the Pentagon nor US Central Command, which oversees Middle East operations, has responded to Business Insider's queries on this incident.

The incident is notable because the F-35, a fifth-generation fighter jet with advanced stealth capabilities built by US defense contractor Lockheed Martin, was made to pierce contested airspace defended by sophisticated air defenses and advanced enemy aircraft and suppress enemy capabilities or feed targeting data to other assets. Last year, Israeli F-35s demonstrated the fighter jet's ability to fulfill this role by striking inside Iran. Though capable, Houthi air defenses fall short of the kind of threats the jet was made to confront.

What, exactly, this means for the jet, if anything, is unclear considering the unknowns in this story. But there are aspects of the F-35 and stealth aircraft in general that are worth keeping in mind when thinking about these reports.

Thinking about stealth aircraft

Billie Flynn, a former Royal Canadian Air Force combat commander and Lockheed employee who was involved with the F-35 program for around 20 years, said that one aspect of stealth, the part most commonly looked at, is an aircraft's radar cross-section — something the size of a ping pong ball or a golf ball or smaller for a fighter aircraft like the F-35.

"We can imagine how impossible that would be to detect high up in the air, many, many miles away," Flynn told BI.

The F-35 — along with the F-22 Raptor, the B-2 Spirit bomber, and its eventual successor, the B-21 Raider — are defined as "very low observable" aircraft, and that capability comes from a combination of factors.

The F-35 was designed with stealth in mind. According to Lockheed, the signature gray paint the jet is coated in at the end of the production line is intended to reduce and absorb radar signals. The aircraft's design also contributes to its low observability by eliminating flat surfaces and right angles, using composite materials, and allowing for the storage of weapons and fuel internally. The engine design also limits emissions.

Those passive capabilities enhance the F-35's stealth, but it also features active systems like an advanced electronic warfare suite that can jam or inhibit enemy radars to prevent detection.

President Donald Trump, who said this week he's not a big believer in stealth, said repeatedly during his first term that the F-35 is "invisible." It is not. These aren't cloaked Klingon warbirds from Star Trek, but they are tough to detect and difficult to hit. But no system is infallible.

The US learned this lesson during the Kosovo War in the late 1990s, when the Yugoslav Army shot down a Lockheed F-117 Nighthawk, marking the loss of one of America's first operational stealth planes.

Nothing is invincible

"Everything is spotable. The idea that you've got a cloaking device is very dangerous," said Richard Aboulafia, an aviation expert and the managing director of the US consulting firm AeroDynamic Advisory.

"The most important asset of the F-35 is not its low observability," Aboulafia told BI, "it is its extremely advanced mission equipment package that allows it to spot dangers and targets, threats and targets." He said that's the real capability.

Aboulafia said that being a low-observable aircraft means that there is less of a risk of being spotted and tracked, not that the plane is entirely stealthy all of the time.

The way a jet is employed, such as if munitions are carried externally in what has been described for F-35s as "beast mode," can compromise stealth. Adversary air defenses can turn on their system at the right place at the right time and get lucky as well.

In the case of the recent media reports, the US F-35 avoided the Houthi missile. But it's unclear whether the jet was actually targeted or if the rebels just fired in that general direction and happened to get somewhat close to the aircraft, forcing evasive maneuvers.

Houthi air defenses are "a significant threat to military and civilian aircraft and platforms operating in the vicinity of Yemen," Gordon Davis, a retired US Army major general and NATO's former deputy assistant secretary-general for its Defense Investment Division, told BI.

Davis, now a non-resident senior fellow with the Center for European Policy Analysis' Transatlantic Defense and Security Program, said that the rebels have the "most capable and sophisticated" air defense array of any non-state actor in the Middle East, thanks to Iranian training, equipping, and assistance.

Houthi air defenses include surface-to-air missile systems of varying ranges, and these have reportedly shot down a number of US military MQ-9 Reaper drones, though not any crewed aircraft.

Davis said that although it is theoretically possible that a Houthi air defense system could have locked onto an F-35 and fired at the aircraft, it's "highly improbable" that a properly operating jet would be struck. That's because the jet is equipped with advanced electronic warfare and self-protection capabilities, like its AN/ASQ-239 system, that can detect and defeat threats. Also, the pilot would appropriately maneuver in response.

"An F-35 would've had to go to great lengths to expose itself enough that any system — whether it be Houthi, or Russian, or Chinese — could actually see it in the air," explained Flynn, the former Canadian commander. "That's almost inconceivable to me."

• A couple of NATO allies are exploring alternatives to the F-35 stealth fighter.
• A handful of countries that operate the aircraft told BI that they are still committed to the jet.
• Analysts said there aren't many good reasons to walk away from the program just yet.

The Trump administration stirred up some turbulence for the F-35 stealth fighter program, but even though a couple of allies have expressed uncertainty, there hasn't been a wave of partners jumping ship, at least not yet.

The Trump administration's dismissive attitude toward Europe's defense and other tensions saw Canada and Portugal reconsider their interest in the F-35 stealth fighter jet — a fifth-generation plane made by US defense giant Lockheed Martin and one of America's top weapons exports.

It opened the door to a possible European alternative to the F-35 Lightning II Joint Strike Fighter. Saab has signaled that there are talks underway about the JAS 39 Gripen fighter.

Other countries that operate the F-35 told Business Insider that they have no plans to walk away from the platform right now. Some emphasized their commitment to the fighter and desire to preserve the close defense cooperation with the US.

Lockheed has said that F-35 sales matters are between the US government and buyers.

The F-35 is in service with militaries around the world and has seen extensive combat experience since its first flight roughly 20 years ago. The world's most expensive weapons program is grappling with maintenance and sustainability challenges, but it is considered a top fifth-generation fighter.

Portugal's defense minister said last month that it should reconsider replacing its F-16s with F-35s. He said the US stance on security issues is concerning. Shortly after, Canada's defense chief said Ottawa would look into possible F-35 alternatives amid tensions with the Trump administration over tariffs and other threats.

Both Portugal and Canada are NATO allies, although Lisbon is not currently an F-35 customer. Ottawa, meanwhile, is an original program participant, which puts it in a somewhat unique position.

A Canadian defense ministry spokesperson previously told BI the country is not canceling its planned F-35 procurement; aircraft deliveries are set to begin next year. They said that the military is "in the early stages of scoping the review in a way that is both efficient and thorough."

So far, Portugal and Canada are the only two countries to publicly suggest they could pivot away. The defense ministries of four F-35 program participants — the UK, Australia, Denmark, and the Netherlands — expressed their continued support for the plane in statements to BI last month.

The UK said that the F-35 is part of its new defense industrial strategy. Australia said it was "committed to continued investment" in the aircraft. Denmark and the Netherlands specifically highlighted their close cooperation with the US and their intentions to preserve the relationship.

Poland, another customer, said its F-35 program will continue on schedule. A defense ministry spokesperson told BI: "Currently, there are no decisions on the possible termination of the agreements signed with the American side."

Germany, likewise, has signaled it is sticking with the program as well. Berlin is waiting for an order of 35 F-35s.

Sticking with the F-35 for now

Analysts pointed to several reasons why countries are staying with the F-35, among them being the commitment to the program and the amount of work that would be required to pivot away from the aircraft to something new.

Richard Aboulafia, an aviation expert and managing director of the US consulting firm AeroDynamic Advisory, explained that many countries already have a large number of F-35s they've ordered and have paid for the planes even if they haven't yet been delivered.

"It's too late to turn back. What can they say?" he told BI.

Aboulafia also said that the F-35 is a better fighter than any of its competition (like the Eurofighter Typhoon jet), and allies would need "very strong reasons" to abandon the aircraft.

Increasingly capable surface-to-air missile systems and fighter upgrades make fifth-generation capabilities appealing, especially as sixth-gen capabilities are still years away.

The contract for the first US sixth-gen fighter aircraft, the F-47, was only recently awarded. And despite claims to the contrary, drone technology isn't to the point that it can replace sophisticated crewed fighters.

Unlike the fourth-generation fighters, the F-35 features all-aspect stealth, advanced avionics, high-end sensors, and networking solutions, giving the jet the ability to execute a range of missions, from air-to-air combat to strike, and also quarterback a fight.

The jet comes in three variants. The F-35A features a cannon, the F-35B is capable of short-takeoff/vertical landing that is useful for amphibious assault ships and some European aircraft carriers, and the F-35C is built for US Navy carrier operations.

Allies overseas operate the A and B variants. Japan has an order for over 100 F-35As and more than 40 F-35Bs, which can be operated from its Izumo-class destroyer vessels. The UK has bought Bs for its Queen Elizabeth-class carriers.

US allies and partners have been able to find key combat solutions for a wide range of missions using the F-35's capabilities. Israel, for example, demonstrated the F-35's combat power in impactful strikes on Iran.

Mark Cancian, a retired Marine Corps colonel and a senior advisor on defense and security at the Center for Strategic and International Studies, said that the F-35's maintenance, training, and parts supply process are too extensive and expensive for a country to change plans on a dime.

"Most countries struggle to maintain a single fighter aircraft. They could not support two different supply chains and training pipelines," Cancian told BI.

While other countries have yet to abandon the F-35 program, they might possibly decide to do so down the road if a more viable alternative presents itself. Right now, though, the jet is really the only fifth-generation aircraft in town, the only option available to the US and its allies.

Aboulafia said some F-35 customers may still have a question mark looming over them. He stressed that the bigger issue is that larger customers still buying F-35s, like the UK and Japan, could shift their focus to other multinational efforts to develop fighter aircraft.

Two potential examples are the Global Combat Air Programme, a project led by the UK, Italy, and Japan to jointly build a sixth-generation fighter, and the KAI KF-21 Boramae, a South Korean-led initiative.

• Some NATO countries are considering alternatives to the F-35 stealth fighter jet.
• The Trump administration's shifted stance towards Europe has allies concerned about reliability.
• Lockheed's business is feeling the trust erosion between the US and its allies, an analyst said.

The Trump administration is throwing some cold water on the once-hot market for Lockheed Martin's F-35 stealth fighter. And that's not the company's only headache.

At least two NATO militaries are weighing alternatives to the F-35 Lightning II Joint Strike Fighter as the US signals in public statements and unintentionally leaked private chats that it is less committed to Europe's defense. Top Trump officials have characterized Europe as a "pathetic" freeloader.

Trump's trade wars and public spats with the leaders of countries buying F-35s pose risks for Lockheed, which makes the fifth-generation F-35 fighter for the US military and foreign customers, aviation experts said.

A reduction in F-35 purchases by foreign buyers would drive up the cost-per-unit of jets, including for the US because the fixed costs can be spread across fewer planes.

Many foreign military sales "are now endangered by these new concerns about US reliability," said Mark Cancian, a retired Marine Corps colonel and a senior advisor on defense and security at the Center for Strategic and International Studies.

To make matters worse for Lockheed, Trump last week selected its rival, Boeing, to build the next-generation F-47 stealth fighter. Lockheed's stock briefly dropped following the contract announcement, and Bank of America downgraded the defense giant, citing the F-47 contract upset.

A Lockheed spokesperson said that "foreign military sales are government-to-government transactions, so anything further will be best addressed by the US or respective customer governments." And on the F-47, the company has said it will continue to work with the Air Force on new capabilities.

The White House did not respond to a request for comment from BI on recent turbulence.

Growing anxiety

The Trump administration's warming position toward Russia and its criticism of NATO countries has triggered a shift in how some members of the alliance view their defense relationship with the US. NATO countries field a variety of US-made weapons, but the F-35 is a top product.

Earlier this month, Portugal's defense minister said that the country should re-consider replacing its arsenal of F-16s with the more advanced F-35s, citing the US stance on security issues as cause for concern.

Canada's defense minister then said the country would review alternatives to the F-35 amid rising tensions with the US over Trump-ordered tariffs and other trade threats.

A Canadian defense ministry spokesperson told BI that Canada is not canceling its planned F-35 fighter procurement, with deliveries set to begin next year. They said the ministry is "in the early stages" of reviewing the current F-35 process "in a way that is both efficient and thorough."

Last week, the chairman of Denmark's parliamentary defense committee said he regretted buying the F-35, citing concerns that the US State Department could abruptly block spare parts needed to maintain the aircraft. He said purchasing American weapons is now "a security risk."

The country's defense ministry told BI that "any limitations in the use of Danish F-35 aircraft are classified information, but Denmark is still open to buying additional F-35 aircraft in the future."

Denmark, like Canada, is an original F-35 program participant. The fifth-gen aircraft has also been sold to another dozen countries in Europe, the Middle East, and Asia. Since the first F-35 rolled off the factory floor nearly two decades ago, over 1,100 jets have been delivered to allied and partner militaries.

Three other F-35 program participants, specifically the UK, Australia, and the Netherlands, voiced their continued support for this program.

The Dutch defense ministry told BI that there's "no reason to assume that the good cooperation with the US in the F-35 program will change or stop," and a spokesperson for the Australian defense ministry said that it is "committed to continued investment" in the F-35.

Other allies, like Germany, have also reiterated their support for the program, even amid lingering uncertainty. A spokesperson for Poland's defense ministry told BI that its F-35 program "is being implemented according to schedule. Currently, there are no decisions on the possible termination of the agreements signed with the American side."

Questioning alliances

NATO allies have not yet made any firm decisions to pull the plug on more F-35 procurement, but unease has replaced a once certain confidence. Analysts and experts say that US allies may be justifiably concerned about the potential leverage the Trump administration could have over them.

There's no kill switch or anything like that for the jets, but the US provides critical additional support for its weapons that makes them effective. American-led maintenance and supply chains, as well as networks and planning support, are essential to the program. Without them, these jets could end up being display pieces costing in excess of $80 million.

As with other weapons systems, the State Department must approve potential F-35 sales to foreign buyers. Trump raised eyebrows last week when he said some US allies might only be able to buy a less-capable version of the coming F-47. The US has sold modified export models of weapons, but the reasoning here was notable.

When he announced that Boeing Co., a longtime leader in stealth aircraft production, will build the sixth-generation Next Generation Air Dominance, or NGAD, fighter, Trump said that allies could purchase a "toned-down" version of the aircraft "because, someday, maybe they're not our allies."

Richard Aboulafia, an aviation expert and the managing director of the US consulting firm AeroDynamic Advisory, said that reduced foreign exports could drive up US purchasing costs. That's not great for the F-35 program.

The jet has faced criticism, including from the cost-cutting Department of Government Efficiency head Elon Musk, for design issues, program costs, and persistent sustainability challenges. There's a risk the plane could be targeted in future budget decisions, though that would be a bigger fight.

"There is a scenario where a bunch of export orders go away, and a bunch of domestic US orders go away," Aboulafia said, adding that this "would make this a much more expensive airplane and, therefore, more vulnerable to cuts."

Lockheed expects to deliver up to 190 F-35s to the US and its allies in 2025.

Retired US Army Maj. Gen. Gordon "Skip" Davis, who previously served as NATO's deputy assistant secretary-general for the alliance's defense-investment division, told BI that while it's possible a US administration could use F-35 support as leverage, "doing so would come at a high strategic cost and provoke resistance from Congress, allies, and industry," not just Lockheed.

Davis told BI there are a number of constraints on the administration after the aircraft has been sold, including contractual obligations, jeopardizing multinational defense cooperation, and driving away foreign interest in the F-35.

He said that allied countries vary in their vulnerability. "Countries without a domestic alternative and not involved in the F-35 component and parts production would be the most vulnerable to such a tactic," Davis said.

There are some European-made alternatives to the F-35, like the Eurofighter Typhoon fighter. However, no European jet matches the fifth-generation F-35, a low-observable networking platform capable of quarterbacking a range of combat capabilities.

• The grinding Ukraine war has seen a rise in hit-to-kill drone interceptions of other drones.
• Kyiv and Moscow are increasingly using drones to take out enemy systems above the battlefield.
• This new tactic is pushing Ukraine to develop drones specifically for interceptor roles.

In the contested skies above Ukraine, a new kind of warfare is rapidly emerging as drones are increasingly sent on new attack missions. Their targets aren't armored vehicles or fighting positions — they are other drones.

Combat footage from the war in Ukraine has repeatedly captured these hit-to-kill intercepts in which a cheap drone slams into another unmanned aircraft. This practice is a cost-effective air-defense option that both the Ukrainians and Russians are using and intently pursuing.

Mykhailo Fedorov, Ukraine's minister for digital transformation, posted on Telegram in April that his country was on the hunt for interceptor drone solutions to shoot down Russian surveillance assets, the front-line eyes for strike drones and Russian artillery, "without wasting air defense assets."

Nataliia Kushnerska, a senior executive in Ukraine's defense industry, told Business Insider that using uncrewed systems in this way "marks the emergence of an entirely new segment of modern warfare — drone-on-drone combat."

A new tactic in the evolving drone war

Drones have dominated the battlefield throughout much of the Ukraine war, being used for land, sea, and air missions. Cheap first-person view (FPV) drones are frequently used to carry out pinpoint strikes on enemy armor and troop positions, while larger systems collect intelligence.

But as the war has dragged on, drones have increasingly been used in an air-defense role to take down enemy uncrewed aerial vehicles (UAVs) carrying out reconnaissance and attack missions. These aerial engagements can, at times, resemble the fierce dogfights of the World Wars.

An outfit that makes combat FPV drones posted in August that its modified drones had taken out 100 Russian UAVs. The Wild Hornets, as the operation calls itself, shared footage of some of the interceptions.

Kushnerska, the chief operating officer of Brave1, a Ukrainian government platform that facilitates innovation within the country's defense industry, said interceptor drones have become "one of the innovations of this war."

The tactic, she said, makes it more difficult for Russia to operate its drones deep behind the front lines and collect data to facilitate missile and drone strikes on Ukrainian positions, which has been a real challenge for Ukraine as Russia pushes to expand its reconnaissance strike complex. This also awards Kyiv more flexibility to carry out its military operations and maneuvers.

Kushnerska said Ukraine was the first to use drones to intercept Russian reconnaissance UAVs, but Moscow has since adapted to the tactic and found ways to evade the interceptors. Now, efforts are underway to improve the systems so they remain effective.

It is the latest iteration of what a senior Ukrainian official previously described to BI as a cat-and-mouse game between Kyiv and Moscow, where each side is constantly attempting to one-up the other in developing drones and other war-related technology.

Samuel Bendett, an expert on drones and Russian defense issues with the Center for Naval Analyses, told BI Moscow is similarly using FPV drones to take out Ukrainian systems and that Russia has also equipped its drones with defenses against interceptor drones, such as electronic-warfare jamming systems.

Bendett said that the Ukrainians "have gotten very successful in fielding their FPV drones against Russian ISR assets, and the Russians have gotten successful, up to a point, with using their FPV drones to go after Ukrainian heavy quadcopter UAVs."

Interceptor drones are limited in range and altitude and often carry less explosive power than more traditional air defenses like missiles. Drones provide Ukraine and Russia with an alternative way to take down aerial threats, one in which the cost of the intercept is often less than that of the system being targeted.

Kushnerska said an interceptor drone typically costs between $2,000 and $4,000. An air-defense missile, on the other hand, could cost hundreds of thousands — or even millions — of dollars. Using drones reduces dependency on more expensive munitions and frees up Ukraine's air-defense units to focus on the bigger threats like Russian aircraft and more deadly cruise and ballistic missiles.

Pursuit of more interceptor drones

For the Ukrainian soldiers tasked with intercepting Russian drones, it's a dangerous mission.

One drone operator in the Ukrainian military told BI that he operates from trench shelters very close to the front lines. He said the pilots are priority targets for Russia, which will use "every single thing at its disposal" to take them out.

The Ukrainian operator said that drone-on-drone combat is increasing. He said he sometimes uses interceptor drones up to five times a week. But Ukraine needs more of them.

Kyiv has taken steps to procure more of these interceptor drones. Last month, for instance, a Ukrainian drone engineering company announced it had completed testing for a new FPV drone designed to take down Russian reconnaissance UAVs, like the Orlan, and was ready for military use.

But there's still more to be done. Valeriy Romanenko, a former air-defense officer who's now a researcher at Ukraine's State Aviation Museum, told BI that Kyiv's interceptor drones are good for slower reconnaissance UAVs at lower altitudes.

However, he said, Kyiv ultimately needs faster interceptor drones to take down Russia's deadly attack drones, like the notorious Shahed-136. In October alone, Moscow fired around 2,000 of these systems at Ukraine, according to Western intelligence.

The Wild Hornets have been working on a new "Sting" UAV to effectively combat the Shaheds, but it's a work in progress.

This hit-to-kill intercept tactic has implications well beyond Ukraine and could be used in future conflicts, too. Mick Ryan, a retired Australian Army major general and strategist, said the use of drones for interceptions will likely be a lasting element of military operations.

"This is a trend that's here to stay unless there is some fundamental breakthrough in very low-cost anti-drone systems, and we're not seeing that at this point," he told BI. "I think this is an enduring kind of capability that many militaries should be looking at."