Al-Shabab has reversed all Somali National Army gains made over the last two years and is now working with the Houthi militant group to expand its capabilities, according to senior U.S. defense officials.

“They are working with the Houthis,” said a senior U.S. defense official, who spoke to reporters on the condition of anonymity. “It’s a bit of a surprise. … It’s quite concerning.”

The official said that the Houthi militants in Yemen view this “nascent” collaboration as a means “to be taken more seriously” as they try to pose a threat to American and British vessels outside the Red Sea.

The Houthis have attacked or threatened U.S. Navy and commercial vessels more than 190 times in the Red Sea and Gulf of Aden since Nov. 19, 2023, Pentagon spokesperson Sabrina Singh told reporters at the Pentagon on Monday. Two attacks on the Palauan-flagged, Ukrainian-owned and Polish-operated bulk cargo carrier M/V Verbena on Thursday left one crew member severely injured, and one crew member remains missing after an attack Wednesday on the Liberian-flagged, Greek-owned M/V Tutor.

“The Houthis claim to be acting on behalf of Palestinians in Gaza, and yet they are threatening the lives of those who have nothing to do with the conflict,” Singh said.

Guled Ahmed, a Horn of Africa scholar at the Middle East Institute, said the Houthis, with help from the Iranian government, aim to establish a new front in the Indian Ocean where al-Shabab can receive advanced missiles and drones. He said the Houthis have already sent three engineers to al-Shabab in southern Somalia to help build sophisticated weapons and bombs for the al-Qaida affiliate.

The United States has been trying to curb the flow of weapons into Somalia for years. In November 2022, the U.S. Treasury Department announced sanctions against eight individuals and one company involved in a yearslong effort to smuggle millions of dollars' worth of weapons between Yemen and Somalia. That smuggling operation aimed to benefit Islamic State’s affiliate in Somalia, but officials say the operation was also helping to arm its al-Qaida-linked rival, al-Shabab, with weapons from Iran.

Al-Shabab expansion

According to senior U.S. defense officials, the Somali National Army’s central Somalia campaign had put al-Shabab “on the back foot” for the past two years.

“But what we've seen is [al-Shabab fighters] have reversed all of those gains over the last six months,” one of the officials said.

Ahmed said the Somali National Army has suffered from poor military strategy, inexperienced field commanders and corruption among leadership, including the theft of food rations, military equipment, weapons and ammunition to sell on the black market.

Al-Shabab is now back at high numbers of between 12,000 and 13,000 fighters because of strong financing and heavy recruitment efforts, following a diplomatic effort between Ethiopia and Somalia’s breakaway region of Somaliland to sign a memorandum of understanding earlier this year.

"They were able to use that to recruit many — who do not like Ethiopia — into al-Shabab ranks,” the senior U.S. official said.

Another senior U.S. defense official said the reversals by al-Shabab are a clear sign that some enabling support must remain once the African Union Transition Mission in Somalia (ATMIS) ends.

“They need all the help they can get to confront the security challenges that are in front of them,” the second senior defense official said. “We're approaching a key milestone.”

Jeff Seldin and Harun Maruf contributed to this report.