On December 29, 2025, Saudi Arabian jets struck the port of Mukalla in southern Yemen. The target was not a Houthi weapons depot or an Iranian-linked supply line. It was a shipment of arms sent by the United Arab Emirates to its allies in the Southern Transitional Council. For the first time in the history of the Gulf Cooperation Council, one member state had directly struck forces backed by another. The headlines focused on Yemen. The story is considerably larger than Yemen.
What is unfolding between Riyadh and Abu Dhabi is not a tactical disagreement over a proxy militia in a peripheral conflict. It is the public emergence of a strategic rupture that has been accumulating for years: a fundamental divergence over what regional order should look like, who should lead it and by what means influence should be exercised. Understanding that rupture and its implications for Gulf stability, requires moving beyond the immediate dramatics of the Mukalla strike and examining the structural contest beneath it.
Two Models of Gulf Power
Saudi Arabia and the UAE intervened jointly in Yemen in 2015 under Operation Decisive Storm, bound together by a shared adversary in the Iranian-backed Houthi movement and a shared alarm at what both governments perceived as the destabilising consequences of the Arab Spring. For several years, that alignment held, reinforced by the Qatar blockade, by coordinated economic pressure on Iran and by the personal rapport between Crown Prince Mohammed bin Salman and UAE President Mohammed bin Zayed.
What that alignment obscured was a deepening divergence in how the two states conceptualise regional influence. Saudi Arabia’s model, in broad terms, is state-centric: Riyadh backs recognised governments and national institutions, supports territorial integrity, and builds coalitions through formal diplomatic and security frameworks. The Saudi investment in the Sudanese Armed Forces, the rehabilitation of Ahmad al-Sharaa’s government in Damascus and the invitation of Somalia’s president to Riyadh all reflect this orientation. States, in Riyadh’s calculus, are the building blocks of a stable regional order – even imperfect ones.
The Emirati model is more transactional and more comfortable with fragmentation. Abu Dhabi has demonstrated a consistent preference for disciplined, controllable partners over unpredictable state institutions – backing the Southern Transitional Council in Yemen, the Rapid Support Forces in Sudan and maintaining commercial and security footholds in Somaliland and Puntland. Where Riyadh sees secessionist dynamics as a threat to the regional order it seeks to lead, Abu Dhabi has shown a greater willingness to work with and in some cases cultivate, sub-state actors that deliver reliable outcomes regardless of their formal status.
These are not merely tactical differences. They reflect incompatible visions of what the post-Iranian-deterrence Middle East should look like and who should shape it.
The Accumulation of Alarm
Saudi concern about Emirati regional behaviour did not originate with the Mukalla strike. What transformed that concern into direct confrontation was the cumulative weight of Emirati activity across multiple theatres simultaneously.
In Sudan, the UAE’s support for the Rapid Support Forces, whose commander Mohamed Hamdan Dagalo had previously sent fighters to assist Emirati proxies in Yemen, has been interpreted in Riyadh not as a calculated commercial and security bet, but as a pattern of actively accelerating fragmentation in an Arab state. Saudi Arabia backs the Sudanese Armed Forces under General Burhan. The two Gulf powers are now on opposite sides of one of the deadliest conflicts in the world, with Riyadh reportedly facilitating a substantial arms arrangement for the SAF and Crown Prince Mohammed bin Salman personally urging President Trump during his November 2025 Washington visit to increase pressure on Abu Dhabi over its Sudan role.
In Somalia, the dynamic follows a similar logic. Years of Emirati commercial and security engagement, through DP World port agreements and military arrangements in Somaliland, Puntland and Jubaland – have been increasingly read in Riyadh as the construction of an Emirati sphere of influence that cuts across Saudi Arabia’s own diplomatic relationships. Somalia’s federal government, backed by Riyadh, moved in early 2026 to cancel its defence agreements with the UAE entirely. Saudi Arabia has since deepened security cooperation with Egypt and Somalia, with both Eritrea’s president and Sudan’s General Burhan received in Riyadh in December 2025 – two leaders united, in part, by shared grievances against Emirati influence in the Horn of Africa.
The final trigger was Israel’s recognition of Somaliland in late December 2025. Saudi Arabia does not publicly subscribe to alarmist interpretations of Israeli regional strategy, but internal assessments increasingly link Emirati positioning in fragile states to a broader pattern of external legitimisation of secessionist dynamics. The concern is not merely strategic but precedential: once fragmentation becomes normalised in Yemen, Sudan and Somalia, the question of where it stops becomes uncomfortably difficult to answer.
Yemen as Inflection Point
The STC’s seizure of Hadramawt and Mahra governorates in December 2025 – areas bordering Saudi Arabia directly, crossed a red line that Riyadh had not previously made explicit. Saudi Arabia’s subsequent military response, its dissolution of the STC and its coordination with Qatar, Oman, Turkey and Egypt to isolate Abu Dhabi diplomatically represented a qualitative shift: from quiet management of the rivalry to active contestation of it.
The UAE’s withdrawal announcement on December 30, 2025 and the STC’s agreement to talks, temporarily arrested the most visible dimension of the confrontation. But the structural conditions that produced it remain entirely unresolved. The STC’s dissolution does not undo the Emirati network of influence in southern Yemen built over a decade and Saudi Arabia’s appetite for reasserting control over the Arabian Peninsula’s periphery has if anything been sharpened by the episode. Neither side currently seeks open conflict. Both appear willing to accept sustained rivalry as the price of defending their respective regional visions.
The GCC’s Structural Problem
The Gulf Cooperation Council was never a deeply integrated institution. Its founding logic was defensive solidarity among similar regimes facing similar threats: internal instability, Iranian revisionism and over time, the political consequences of oil dependency. It was not designed to manage strategic competition between its two most capable members.
That design limitation is now fully exposed. The GCC has no meaningful mechanism for mediating a Saudi-Emirati rivalry playing out across Yemen, Sudan, Somalia and Syria simultaneously. Its secretariat lacks the authority and the member states lack the shared interest to enforce the kind of internal coherence that would be required. The Saudi-UAE contest is, in institutional terms, happening largely outside the GCC’s framework: through bilateral diplomacy, arms arrangements, airspace restrictions and proxy positioning that the Council has neither the mandate nor the leverage to constrain.
This has implications beyond bilateral relations. The United States has long treated a broadly unified GCC as a foundational assumption of its Gulf security posture: a coherent bloc of aligned partners capable of coordinated responses to shared threats. That assumption requires revision. Washington is now managing relationships with two Gulf powers that are pursuing actively competing regional strategies, with the explicit ambition of determining who will define the Arab world’s next order. Riyadh has signalled its displeasure about Emirati conduct directly and personally to President Trump. The Trump administration’s response: maintaining close ties with both MBS and MBZ simultaneously, may be untenable as the rivalry deepens.
Policy Implications
Several conclusions merit attention from policymakers navigating this environment.
The rivalry is structural, not episodic. Analysts have periodically described Saudi-Emirati tensions as temporary disagreements amenable to quiet resolution between the two leaderships. The events of late 2025 and early 2026 suggest otherwise. The divergence is rooted in incompatible regional visions that have crystallised as both states have grown more confident in pursuing independent strategies. Managing it requires a long-term framework, not crisis-by-crisis intervention.
Fragmentation dynamics deserve greater analytical attention. The emerging regional contest between a Saudi-led state-sovereignty coalition – encompassing Egypt, Turkey, Sudan and Somalia in various configurations and an Emirati-linked network comfortable with sub-state actors and secessionist outcomes is reshaping political alignments across the Red Sea basin. The implications for regional stability, maritime security and the management of fragile states extend well beyond any single conflict theatre.
The GCC requires institutional reform or honest reassessment. Treating the Council as an effective multilateral framework for Gulf security coordination when its two leading members are in open strategic competition produces analytical distortions. Either the GCC develops genuine dispute-resolution mechanisms, or its actual function as a political forum rather than a security institution – should be explicitly acknowledged in regional policy frameworks.
Washington cannot remain equidistant indefinitely. A transactional approach that preserves ties with both Riyadh and Abu Dhabi may serve short-term US diplomatic interests, but risks allowing a rivalry with significant destabilising potential to deepen without any external constraint. At some point, the United States will be asked – directly or indirectly, to clarify whose regional vision it supports. The absence of a considered answer to that question is itself a strategic choice with consequences.
Conclusion
The Mukalla strike of December 29, 2025, was not a moment of rupture. It was the public confirmation of a fracture that had been widening for years. Saudi Arabia and the UAE remain allies in formal terms, bound by shared membership of the GCC, by common economic interests and by a history of cooperation against shared adversaries. But the relationship has entered a phase of structured competition – episodic, proxy-driven and increasingly difficult to contain within the diplomatic conventions that previously kept it quiet.
The contest between Riyadh and Abu Dhabi is, at its core, a contest over what the post-Iranian-deterrence Middle East will look like and who will lead it. That question will not be settled quickly, and its resolution will shape regional dynamics across a wide arc of conflicts from the Arabian Peninsula to the Horn of Africa. Recognising the rivalry for what it is, not a bilateral difficulty to be managed, but a structural feature of the emerging regional order, is the first step toward policies adequate to its consequences.