War on Gaza: Could unmanned submarines be a gamechanger for the Houthis?

For several months now, Yemen's Ansar Allah movement (more commonly referred to as the Houthis) has managed to bring much of the traffic in the Red Sea to a halt.

Using mainly cheap drone technology, the Houthis have provoked fury in western capitals over their disruption of maritime traffic, and despite a fierce military response from the US and UK, the group has pledged to effectively make the seas of the Middle East no-go areas for Israel and its supporters as long as the bombardment of Gaza continues.

As they continue to step up their operations, the group have unveiled a new addition to their arsenal: submarine technology.

"We introduced the submarine weapons into the confrontation in the Red Sea, and it is a weapon that will worry the enemy," Yemen's Al-Masirah TV channel quoted Abdulmalik al-Houthi as saying on Thursday.

That same day the group warned shipping insurers and firms that any Israel-flagged vessels or ships wholly or partially owned by Israelis would be banned from the Red Sea, Gulf of Aden and Arabian Sea.

According to Reuters, statements sent to shipping insurers from the Houthi's Humanitarian Operations Coordination Center - which the group established to monitor passage of non-prohibited shipping - also said that vessels owned by US or British individuals or entities, or sailing under their flags, were now banned.

What does this new addition to the Houthis' arsenal mean for their ongoing operations in the region?

Cheap and effective

Last week, the US said it had launched five strikes against Houthi mobile anti-ship cruise missiles, as well as an one unmanned underwater vessel (UUV) and one unmanned surface vessel (USV).

So far, the Houthis have not gone into any detail about the technology, and much of the analysis is speculative, with many quick to point the finger at the group's ally Iran, which does manufacture naval drones.

According to a report by the US Naval Institute, the photographs released by the US military last week showed "a propeller (screw) section that is consistent with UUVs used by Iran".

'I think there is a lot, unfortunately, that they will surprise us with'

- Farea Al-Muslimi, Chatham House

"The UUV, along with those seen in Iran, appears similar to a torpedo or one-way attack underwater drone (OWA-AUVs)," said the report.

"Generally, these have a greater range than a torpedo but are slower, making them most effective against static targets such as ships in port or at anchor."

The fundamental benefit of UUVs is that they are considerably less easy to detect as well as being substantially cheaper than missiles.

A naval drone previously publicised by the Ukrainian government - used to sink Russian ships in the Black Sea - reportedly cost $250,000, which the BBC described as "cheaper than many types of long-range missiles".

Earlier this month, a Ukrainian naval drone, with a payload capacity of 320kg of explosives, reportedly struck a Russian landing ship in the Black Sea, sinking it.

The remote-controlled drones, which are highly manoeuvrable and limit the loss of human life, have been hailed for allowing Ukraine to punch above its weight compared to the more militarily advanced Russians.

Farea Al-Muslimi, a research fellow at Chatham House, told Middle East Eye that the Houthis clearly did not come into possession of the technology overnight and its revelation was strategically timed.

"We haven't seen even half of the Houthi capabilities in submarine technology," he said. "I think there is a lot, unfortunately, that they will surprise us with."

Expected impact

Alberto Rizzi, a visiting fellow and associate researcher at the European Council on Foreign Relations (ECFR), said that Ukraine had already proven the potential threat posed by such drones.

"They can hit ships in more vulnerable parts and are much more difficult to intercept and target, making them a serious threat to tankers or cargo vessels," he explained.

"However, undersea and surface drones are much more complex than aerial ones to develop and build and, although Iran has some capabilities in this domain, it is unlikely that the Houthis have wide numbers of them in their arsenal."

The impact of the Houthis' Red Sea operations is already being starkly felt.

According to the Suez Canal Authority chief, revenue from Egypt's Suez Canal dropped by almost half in January following the beginning of their attacks.

'Technological developments are bringing down the economic and technical threshold to manufacture drones that can be employed against ships'

- Alberto Rizzi, ECFR

The official said that income had dropped to $428m in comparison to $804m for the same period in 2023 and that the number of ships navigating the canal fell by 36 percent.

The Shanghai Containerised Freight Index (SCFI), meanwhile, said global shipping costs were up more than 300 percent as a result of the Houthi blockade. 

Muslimi said that "perception" was as important as anything else, and that even if the US and UK air strikes actually harmed the Houthis, companies and insurers had already effectively written-off the route for the foreseeable future.

"Yemen is 44 times bigger than Lebanon and the maritime is huge. It's really easy to make an eruption there," he explained. "It doesn't take a rocket scientist to make a rocket any more."

With the death toll in Gaza close to 30,000, there is no indication that the Houthis plan to stop their operations.

As such, Rizzi suggested that the new naval drones were unlikely to have much immediate impact since those routes were increasingly being avoided anyway.

Nevertheless, it could easily point the way forward for other groups wanting to leverage comparatively low military strength against more powerful enemies.

"Sea routes, despite their apparent simplicity, are extremely complex and vulnerable: technological developments are bringing down the economic and technical threshold to manufacture drones that can be employed against ships," he said.

"This makes other armed groups in proximity of maritime chokepoints a future danger, as they can draw inspiration from the Houthis and carry out similar attacks elsewhere."