• 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."

• The Trump-ordered airstrikes are an intensified campaign against the Houthi rebels in Yemen.
• The ramped-up campaign goes beyond the Biden administration's "defensive posture," an expert said.
• It's likely to take months to see whether airstrikes — without other forces — deter the Houthis.

The Trump administration's airstrikes against the Houthi rebels in Yemen — discussed by top officials in the unclassified Signal chat group — are a dramatic escalation of the US's confrontation with the group for its attacks on commercial ships and naval vessels, regional experts told Business Insider.

"The Trump-era strikes are broader in scale and formed as part of a sustained campaign targeting not only Houthi infrastructure — such as hideouts, stockpiles, and military assets — but also the group's leadership," Freddy Khoueiry, a global security analyst for the Middle East and North Africa at the risk intelligence company RANE, told Business Insider.

"This mirrors Israel's approach during its conflict with Hezbollah, where efforts to degrade military capabilities were accompanied by systematic strikes on field commanders, eventually reaching senior leadership figures and the upper echelon."

This focus bears out from the Atlantic's bombshell reporting on the Signal group: "The first target - their top missile guy - we had a positive ID of him walking into his girlfriend's building and it's now collapsed," National Security Adviser Michael Waltz texted. "Excellent," Vice President JD Vance replied.

Regional experts cautioned it is likely to take months to see whether more airstrikes and targeting the Houthi movement's leaders will end its attacks on Israel and merchant ships. The Houthis may also end these attacks with a new Gaza ceasefire or an Israeli return to the existing one.

The Houthis began a campaign targeting and hijacking commercial ships transiting the Red Sea shortly after the October 2023 Gaza war began; Hamas, like the Houthis, are armed and trained by Iran. The Yemeni militants also launched intermittent drone and missile strikes against Israel.

The Biden administration responded by dispatching the US Navy to protect commercial shipping near the Bab al-Mandab strait and repeatedly struck military targets in Yemen like missile launchers, underground storage facilities, radars, and air defenses. These efforts failed to end the attacks. The State Department redesignated the Houthis a foreign terrorist group in March.

The Houthis halted attacks targeting Israel and commercial shipping following the January ceasefire in Gaza. On March 12, the group announced they would resume attacks if Israel did not stop blocking aid to the coastal Palestinian enclave. Three days later, the Trump administration ordered the intensified campaign.

In the private group chat on Signal that, in an extraordinary turn, accidentally included the editor-in-chief of The Atlantic, Secretary of Defense Pete Hegseth pressed for the strikes over Vance's qualms, in part by arguing that only a tougher air campaign would deter the Iran-backed rebel group.

"I see it as two things: 1) Restoring Freedom of Navigation, a core national interest; and 2) Reestablishing deterrence, which Biden cratered," Hegseth texted

In an interview with ABC's "This Week" show, Hegseth contrasted Biden's "pinprick, back-and-forth — what ultimately proved to be feckless attacks" with Trump's "overwhelming response that actually targeted multiple Houthi leaders and took them out."

The US is only the latest force to confront the Houthis. Saudi Arabia led a multinational coalition against the Houthis in a war that began in 2014 after the Houthis captured Yemen's capital, Sanaa, from the internationally recognized government and ended with a ceasefire in 2022 that's still in place.

The new US campaign bears similarities to the Israeli approach. After the Houthis successfully hit Tel Aviv in a drone attack last July, Israel also launched several long-range airstrikes against the group and threatened to hunt down its leadership. Since beginning its current campaign on March 15, the US has asked Israel not to respond to the latest Houthi missile attacks, which Israeli air defenses successfully intercepted, by stating: "Leave it to us."

Compared to Hezbollah in Lebanon, Israel has relatively little intelligence on the more distant Houthis, a deficiency it has recently sought to rectify. This is in stark contrast with how deeply it infiltrated Hezbollah. In addition to injuring over 3,000 Hezbollah members with booby-trapped pagers and walkie-talkies in September, Israel also assassinated the group's long-time leader, Hassan Nasrallah.

Israel's strikes sought to inflict economic damage on the Houthis through strikes on energy facilities and ports controlled by the group.

"The Biden administration largely adopted a defensive posture, engaging in reactive, tit-for-tat operations," Mohammed Al-Basha of the Basha Report, a Virginia-based Risk Advisory, told BI. "The Trump administration, however, is not pursuing regime change or aiming to topple the Houthis. It has deliberately avoided targeting infrastructure that would harm the civilian population."

"It is an offensive posture designed to reestablish deterrence," Al-Basha said. "President Trump has made it clear that continued Houthi attacks on US naval vessels in the Arabian and Red Seas will no longer be tolerated."

"While it is still too early to fully assess the campaign's effectiveness, even the Houthis have acknowledged that they are suffering losses and casualties from the ongoing airstrikes."

The airstrike campaign faces similar problems to those that came before.

The Houthis are "deeply entrenched in Yemen's challenging terrain" and may have prepared for a protracted campaign, said RANE's Khoueiry, who thinks only a long-term air campaign could deter the Houthis.

Independent Middle East analyst Kyle Orton believes it's "too early to tell" if Trump's overall approach will ultimately yield any more than the Biden administration achieved.

"The strikes in themselves have done little to damage the Houthis, and it remains to be seen if this was, as some administration rhetoric has suggested, the opening volley in a sustained campaign," Orton told BI.

A significant shift in US policy towards Yemen, in Orton's view, would entail a sustained air campaign that coordinated action with Arab allies and the recognized Yemeni government to recapture territory held by the Houthis.

"There is, however, little indication Trump is willing to get 'entangled' in the Middle East so seriously," Orton said.

Paul Iddon is a freelance journalist and columnist who writes about Middle East developments, military affairs, politics, and history. His articles have appeared in a variety of publications focused on the region.

Top Trump officials included the editor of the Atlantic in a Signal group chat discussing plans to strike Houthis in Yemen. We explore Washington's reaction in this video collaboration between Politico and Business Insider.

• Signal's founder, Moxie Marlinspike, poked fun at the military group-chat leak in a post on X.
• He used the incident as an opportunity to ironically promote the platform.
• US officials, however, have expressed alarm over the security breach.

A major security leak involving the secure messaging platform Signal sparked widespread alarm throughout the country — but the platform's founder didn't appear very concerned.

In a post on X on Monday afternoon, Moxie Marlinspike, whose real name is Matthew Rosenfeld, poked fun at the group message leak and used it to ironically promote the "many great reasons to be on Signal."

"Now including the opportunity for the vice president of the United States of America to randomly add you to a group chat for coordination of sensitive military operations," the founder of the platform and its former CEO wrote in the post.

Marlinspike was referring to Monday's news that The Atlantic's editor in chief was accidentally added to a Signal group chat called "Houthi PC small group."

"PC" referred to the principal committee, and the chat was primarily made up of senior US officials, including Vice President JD Vance, Defense Secretary Pete Hegseth, Director of National Intelligence Tulsi Gabbard, and Secretary of State Marco Rubio.

The chat's participants were discussing forthcoming strikes on Yemen's Houthi rebels, Jeffrey Goldberg, The Atlantic's editor in chief, revealed in an article.

Marlinspike's reaction is in sharp contrast to that of that of Democratic and Republican officials, many of whom expressed alarm at the security leak.

Republican Sen. John Cornyn of Texas told reporters the incident "sounds like a huge screwup" and that "somebody dropped the ball." Republican Sen. Jim Risch of Idaho said Tuesday there will be an investigation into the incident, The Hill reported.

Marlinspike wasn't the only social media user to poke fun at the snafu. However, comments on his post were mixed, with some blaming the officials who made the mistake and others saying that the platform should improve its security.

On Tuesday, Signal wrote in an X post that there has been "misinfo flying around that might drive people away from Signal and private communications."

Signal cited a Tuesday report from NPR in its post. In its report, NPR said it obtained a Pentagon email from March 18, warning employees about a potential Signal vulnerability.

"The memo used the term 'vulnerability' in relation to Signal—but it had nothing to do with Signal's core tech. It was warning against phishing scams targeting Signal users," Signal wrote on X.

"Phishing isn't new, and it's not a flaw in our encryption or any of Signal's underlying technology. Phishing attacks are a constant threat for popular apps and websites," the company continued.

Signal is a nonprofit, open-sourced, end-to-end encrypted messaging platform that has emerged as one of the most popular messaging apps over the last few years. Only recipients can see messages, so it's commonly used by journalists, government officials, and tech giants.

Signal and Marlinspike did not respond to requests for comment from BI.