The strategic ambitions of Saudi Arabia and the UAE have been diverging in Yemen – to the detriment of hopes for peace on the ground.

In the evening of 18 January, a missile struck the mosque of a military camp in Marib, killing 116 men serving in Yemen’s Presidential Guard. The head of the Saudi-backed, internationally recognised government (IRG), President Abdrabbuh Mansur Hadi, promptly accused the rebel Houthi movement, calling the strike a “cowardly and terrorist” act. The Saudi foreign ministry said the incident “reflects [the Houthis’] disregard for sacred places and for Yemeni blood.” Most international observers also presumed Houthi involvement, not entirely unreasonably given the flare-up of fighting in the area in the previous weeks.

But, within hours, the Houthis had denied their involvement. Hadi’s own minister of transport later called for an independent investigation into who was behind the strike. And his government’s interior minister even explicitly suggested Emirati or Saudi involvement.

After Hadi’s IRG was ousted by the Houthis in 2014, Saudi Arabia and the UAE became the two core decision-makers in a coalition of countries that sought to return Hadi to power. So how can it be that these countries could be suspected of carrying out the strike on his Presidential Guard?

To understand how, it is important to consider the role of the Southern Transitional Council (STC), which demands secession for the south of Yemen. The 116 presidential guards had been training in Marib in anticipation of deployment to Aden, in Yemen’s south, under the auspices of the Riyadh Agreement. This accord was signed last November to reconcile Hadi’s IRG, whose principal sponsor is Saudi Arabia, and the STC, which receives significant UAE backing. The STC was established in 2017, after which time the UAE increased its support behind it. This is largely due to the UAE’s desire to influence the south and the ports along southern Yemen’s coast, which are key to its strategy to control the maritime routes around the Arabian Peninsula.

In recent years, military clashes broke out between the STC and the IRG, primarily in Aden and the island of Soqotra. While these were normally temporarily solved through Saudi mediation, last August the STC moved, successfully, to expel the IRG government and its forces from Aden, which it was using as a temporary capital after losing Yemen’s capital, Sana’a, in early 2015.

The UAE’s strategic desire is to influence the south and control the maritime routes around the Arabian Peninsula 

As little more than a government in exile, the IRG was now a serious problem for Saudi Arabia which, by that time, had effectively become the coalition’s sole decision-maker. For some time, Saudi Arabia’s and the UAE’s strategic ambitions – in the Gulf more broadly and in Yemen in  particular – had already diverged. Last summer, having abandoned the main military strategy to defeat the Houthis, namely the offensive on Hodeida, the UAE announced its intention to withdraw  completely from Yemen, and it is the prospect of their protector’s departure that may have contributed to the STC leaders’ decision to move to expel Hadi from Aden.

Finding themselves left exclusively in charge of coalition involvement in Yemen, the Saudi authorities called for negotiations to solve the crisis between the IRG and STC as the two main national members of the anti-Houthi coalition. Indirect meetings started in Jeddah within days. For Saudi Arabia, maintaining unity within the coalition and the official government was essential for it to retain credibility as a power-broker in Yemen. In the weeks that followed, the UAE did express support for Saudi Arabia’s efforts – but it did not prevent its STC allies from clashing with IRG fighters on the ground. And, by the end of August 2019, the UAE was carrying out air strikes against IRG forces in and around Aden in support of its STC clients, forcing the IRG to appeal to the Saudis to prevent such attacks.

So it comes as no surprise that it took three months from the initiation of negotiations by the Saudis for the Riyadh Agreement to be signed. And its unrealistic two-month timetable for full implementation was then promptly broken, and military confrontations between the STC and IRG forces continued for control of territory in Abyan and Shabwa governorates. In Aden, STC forces tried to prevent the Saudis from moving into certain sites. On 9 January, a new timetable was set for withdrawal of military forces to pre-August positions and gathering of heavy weapons in Saudi-managed sites. After initial indications of progress, tensions increased significantly when it emerged that the STC had previously removed their operational materiel away from Aden into its rural strongholds.

Since the signing of the Riyadh Agreement, the UAE has made no further assertions of support for the agreement; nor has there been any evidence of the UAE placing pressure on the STC to comply with its provisions. In this context, the list of potential perpetrators of the 18 January military camp mosque attack is longer than Hadi liked to make out when he pointed to the Houthis. Even the fact that it is credible that the UAE could have ordered the attack means that the Riyadh Agreement as a whole is under serious threat and, with it, the future of Saudi-UAE cooperation in Yemen and beyond.

Read more on: The Middle East and North Africa, The Gulf, Yemen

The European Council on Foreign Relations does not take collective positions. This commentary, like all publications of the European Council on Foreign Relations, represents only the views of its authors.