The United Arab Emirates and Saudi Arabia are locked in a fierce dispute over Yemen’s future. Saudi Arabia accuses the UAE of threatening its national security through support of the Southern Transitional Council (STC), which seeks independence for southern Yemen. This conflict risks igniting a civil war in southern Yemen and may spread to Sudan and the Horn of Africa, where both countries back opposing sides. The UAE has backed the STC, a separatist group gaining strength in southern Yemen. Many believed the UAE would advise the STC to delay declaring independence in favor of negotiations. However, the STC recently seized major areas, including Hadramaut and oilfields, extending control over much of former South Yemen. Saudi Arabia responded by bombing vehicles arriving at Mukalla port, linked to the UAE and STC. Riyadh said, “The kingdom stresses that any threat to its national security is a red line, and the kingdom will not hesitate to take all necessary steps and measures to confront and neutralise any such threat.” The STC, recognized in 2019 with seats on Yemen’s Presidential Leadership Council, feels sidelined and demands more power. UAE support keeps growing despite Saudi diplomatic efforts pressing for a rollback. Abdulkhaleq Abdulla, Emirati political scientist, defended UAE’s stance: “The UAE does not let down nor abandon its allies. It supports them with generosity and political and military abundance.” From Riyadh, voices warn of escalating dangers. Farea al-Muslimi, Gulf expert at Chatham House, said, “The dispute now appears to be moving toward a more direct confrontation, with Saudi Arabia publicly accusing the UAE of actions that threaten its national security.” He compared it to the 2017 Qatar crisis and warned the Houthis could benefit from this rivalry. Western powers back Saudi Arabia’s vision of a unified Yemen but are cautious in openly criticizing the UAE. The rift between these Gulf partners marks a new and risky chapter in regional politics.