Since Nov. 2023, the Ansarullah movement has shifted its focus from the Yemeni civil war and the sluggish peace talks with Saudi Arabia to conducting naval operations in the Red Sea and the Gulf of Aden. At the offset, the group—better known as the Houthis—declared that it would target only vessels heading to or from Israel. The declared aim was to pressure Tel Aviv to cease “aggression” against Gaza and to allow humanitarian aid into the Palestinian coastal enclave. However, many of the targeted vessels have no apparent connection with Israel.

Moreover, in response to the ongoing UK and US airstrikes in Houthi-held areas that began in Jan. 2024, the Yemeni group has expanded its list of...