In January, U.S. forces conducted two operations to stop vessels smuggling lethal aid from Iran to Yemen. The first took place on January 11, when U.S. Navy SEALs conducted a nighttime raid of a dhow off the coast of Somalia. The second was on January 28, when a forward deployed U.S. Coast Guard vessel interdicted a dhow in the Arabian Sea.

The seizures fit an ongoing pattern of supply in which parts of advanced weapons are smuggled from Iran to be assembled by the Houthis in Yemen. A press release issued by U.S. Central Command (CENTCOM) said the January 11 operation was the "first seizure of advanced Iranian-manufactured ballistic missile and cruise missile components by the U.S. Navy since November 2019." That date refers to a November 25, 2019, interdiction operation by the crew of the USS Forrest Sherman that turned up components for the "351" (Quds-1) land-attack cruise missile. But allied navies have seized Iranian-made missile components bound for Yemen more recently, including during British-led operations in February 2022 and February 2023.

The January interdictions took place against a backdrop of ongoing Houthi missile and drone attacks against commercial ships transiting the Red Sea. The decision to publicize both operations shortly after their completion—a departure from past practice—suggests that the U.S. government is eager to highlight the link between the Iranian-supplied items and the seemingly unending Houthi strikes. The press release for the January 11 operation asserts that the interdicted components are used for weapons that the Houthis have employed against merchant shipping.

Together, the operations present compelling evidence that Iran continues to violate the arms embargo imposed by U.N. Security Council resolution 2216, which prohibits the direct or indirect supply, sale, or transfer of weapons to the Houthis.

The January 11 Operation

The CENTCOM press release detailing the January 11 operation stated that the seized items included "propulsion, guidance, and warheads for Houthi medium range ballistic missiles (MRBMs) and anti-ship cruise missiles (ASCMs), as well as air defense associated components."

Items seized on January 11, 2024. Credit: U.S. Central Command

A photo showing some of the items supported this assertion. In the image are five liquid-fuel MRBM engines, a turbojet engine for a cruise missile, parts of a Ghadir ASCM including a rocket booster and warhead, and what appear to be 14 long-range, dual-view, swivel-mounted cameras. The wooden pallet in the image, which has a standard size of 40 by 48 inches, gives a sense of the scale of the items.

The five liquid-fuel ballistic missile engines are particularly noteworthy. In a September 2023 military parade, the Houthis unveiled a MRBM called Toufan. Displayed on a trailer was not only the missile itself, but, separately, an engine standing upright behind it. The Toufan appears to be an exact copy of the Iranian Ghadr missile, the Houthis’ "Made in Yemen" claim notwithstanding. If there had been any doubt that Iran had supplied the weapon, the U.S. interdiction puts that to rest, as the engines in the CENTCOM photo are the very same model that appeared in the parade in September.

The Houthi Toufan missile and its engine on display during a military parade. Credit: Houthi media.

Finally, the location of the January 11 operation was unusual, although not especially surprising. U.S. forces said they intercepted the dhow "near the coast of Somalia," in contrast to the usual formulations of the "Arabian Sea" or the "coast of Yemen." Although open to interpretation, the specific mention of Somalia suggests the goods may have followed a somewhat indirect route, or perhaps the vessel was even loaded at a Somali port. This would not be new: a press report in 2017 alleged that Iran was using Somalia as a waypoint for sending supplies to Yemen. Still, it is a reminder of the varied and circuitous paths by which Iran has armed the Houthis in recent years.

The January 28 Operation

The January 28 operation turned up less advanced items. The CENTCOM press release stated that "the boarding team discovered over 200 packages," including components for MRBMs, but no such components were readily apparent in the photos that accompanied the release.

Items seized on January 28, 2024. Credit: U.S. Central Command

Interestingly, though, the seized items included unmanned underwater and surface vehicle (UUV/USV) components. The Houthis' use of USVs, sometimes referred to as waterborne improvised explosive devices, dates back to at least February 2017, when they used one to attack a Saudi Royal Navy frigate. By 2020, according to the UN Panel of Experts on Yemen, their use of this type of weapon had become a regular occurrence. On January 4, 2024, a Houthi USV got within a few miles of a U.S. Navy vessel in the Red Sea before detonating, and since then the U.S. Navy has intercepted and destroyed several similar weapons. Houthi USVs are made in Yemen by outfitting locally available patrol boats or fishing skiffs with explosives and remote guidance systems using parts supplied by Iran.