The destroyer USS Carney defeats a combination of Houthi missiles and drones in the Red Sea in October 2023, according to the Navy. (Aaron Lau/U.S. Navy)

Increasingly advanced technology used by Iran-backed Houthis against ships in the Red Sea is raising the chances of a successful militant strike on U.S. forces, analysts and former defense officials say.

A replenishable supply of sophisticated Iranian and Russian weapons is bolstering the Houthis, whom U.S. forces have repeatedly attacked this week at dozens of sites across Yemen in a bid to cripple their offensive and command capabilities.

The Houthis have improved tactically since beginning their assaults on commercial and military shipping following the outbreak of the Hamas-Israel war, U.S. Navy officials have said.

Now they may be acquiring hydrogen fuel cells to power drones, which could give them new reconnaissance capabilities.

An F/A-18E Super Hornet launches from the flight deck of the aircraft carrier USS Harry S. Truman on March 19, 2025, in Middle East waters. The U.S. has recently ramped up its efforts to degrade Houthi capabilities, launching dozens of airstrikes at the group’s weapons stashes and command sites. (U.S. Navy)

It would only take one strike and some American casualties in the Red Sea to draw the U.S. into a prolonged conflict in the Middle East, Nadwa Al-Dawsari, a nonresident fellow at the Washington-based think tank Irregular Warfare Initiative, said recently during a briefing sponsored by the Middle East Institute. 

“It’s a matter of when, not if,” said Al-Dawsari, adding that Navy officials have told her that some Houthi strikes have come dangerously close to U.S. ships.

In August, a weapons shipment seized by Yemeni National Resistance Forces uncovered hydrogen fuel cells, according to a March 12 report by Conflict Armament Research. The U.K.-based independent research group tracks illicit arms flows.

In this screenshot from a Navy video, USS Gettysburg launches a Tomahawk cruise missile during strikes against Houthi targets in Yemen on March 15, 2025. (Facebook/U.S. Navy)

The discovery of the Chinese canisters mislabeled as oxygen was startling because it was the first time they had seen the technology used for drones by a non-state actor, said Taimur Kahn, the research group’s, head of regional operations for the Persian Gulf.

The canisters likely were acquired commercially and there was no evidence of Chinese government involvement, he added.

Hydrogen fuel cells would allow some Houthi drones to fly higher and longer than those powered by other means, Kahn and other analysts said.

The U.S. Coast Guard fast-response cutter USCGC Clarence Sutphin Jr. seized advanced conventional weapons and other lethal aid originating in Iran and bound for Houthi-controlled Yemen from a vessel in the Arabian Sea, Jan. 28, 2024. (U.S. Central Command)

“The Houthis may not need fuel cell-powered drones to conduct one-way attack missions in the Red Sea, but drones at 10,000 feet on long-endurance missions could find targets more than 100 miles away using passive electronic sensors or visual and infrared cameras,” said Bryan Clark, a retired Navy officer and director of the Hudson Institute’s Center for Defense Concepts and Technology.

That capability could come in handy as the Houthis work to find alternatives to radar and command centers destroyed in recent U.S. strikes, Clark said.

Hydrogen fuel cells also could be useful in powering underwater drones because they have a lower sound and heat signature, making them more difficult to detect, analysts said.

“(The Houthis) have realized in their sort of learning curve in attacking shipping that if you want to sink a vessel, hitting it from above doesn’t work, hitting it on the water line may or may not work, but hitting it under the water definitely works,” said Ian Ralby, a maritime law and security expert and founder of I.R. Consilium, a research and consulting firm.

The Pentagon acknowledged Houthi counterattacks in response to their strikes this past week but said they haven’t come close to U.S. ships yet.

There were at least a few Houthi attacks last year that required added defensive measures. In January 2024, the destroyer USS Gravely had to use its close-in weapons system to shoot down a cruise missile that came within a mile of the ship.

Houthi fighters also have employed swarm drone attacks and upgraded ballistic missiles, Navy officials said last year.

Choking off Houthi access to weaponry and advanced technology is a vexing problem for the U.S. and its allies with few options or quick solutions, Ralby and other experts said.

U.S. naval forces in recent months have interdicted weapons bound for the Houthis. They also work through the Combined Maritime Forces based in Bahrain to stop illicit cargo from reaching militants through the Red Sea, Persian Gulf and nearby waters.

But the Navy doesn’t have the number and types of ships needed to interdict every small trading vessel that travels from Iran to Yemen, said Thomas Warrick, a nonresident senior fellow at the Atlantic Council and the former deputy assistant secretary for counterterrorism policy at the Department of Homeland Security.

A blockade only could be achieved through a declaration of war, something the U.S., Europe and other partners likely would be unwilling to do. A yearslong blockade imposed by Saudi Arabia in 2015 kept aid from reaching starving Yemenis, creating a humanitarian crisis.

While a stepped-up international effort to inspect ships is needed and possible, the problem isn’t limited to the sea. Commercial componentry also is moved by air freight companies, Ralby said.

Seemingly innocuous items are delivered to different locations for later assembly. It’s a method that helped Ukraine destroy or disable more than a third of Russia’s Black Sea Fleet, he said.

“And now what we’re seeing is essentially a replication of that in Yemen where you can potentially move non-weapon parts of weapons that assemble to be much more lethal than a single firearm,” Ralby said.

A better intelligence picture of the group’s supply chain and a partnership with Yemeni government forces is needed to keep weapons out of Houthi hands, Ralby and other analysts said.

In addition to U.S. military actions, a more comprehensive approach, such as broader regional involvement in interdicting Iranian ships headed to Yemen, would better prevent arms shipments from getting through, said retired Gen. Joseph Votel, commander of U.S. Central Command from 2016 to 2019.

“We have not effectively done that,” Votel said.