This article examines the security implications of the Saudi-led Arab Coalition’s military intervention in Yemen (2015–2022), launched to restore the legitimate authority seized by the Houthis, officially known as Ansar Allah (Partisans of God)—an Iran-aligned Zaydi Shia group. It addresses two core questions: why did the coalition fail to achieve its stated objectives, and what lessons can be drawn for the Gulf Cooperation Council’s (GCC) future security frameworks? In doing so, the article explores three interrelated dimensions of the coalition’s intervention and the strategic lessons derived from them. First, the motives behind and consequences of Saudi Arabia’s militarised approach. Second, the strategic, institutional and operational shortcomings of the ad hoc coalition, and the resulting need for a more strategic security alliance in the future. Third, the limitations in the reliability of GCC’s extra-regional security partnerships, particularly with the United States, and the need to rethink future alignments.