Saudi Arabia and the United Arab Emirates have sought to present a united front in an attempt to ward off a potential war in Yemen between their surrogate armies.

Yemen’s Saudi-backed government was ousted last month from key areas in the south by UAE-supported southern separatists, exposing simmering divisions between the two Middle East allies, who are fighting a joint campaign against the Iran-linked Houthi rebels.

In a joint statement released by both countries’ state media on Sunday, the Gulf powers “reaffirmed continued support for the legitimate government of Yemen” and called on warring parties to immediately cease “all military operations” and “stop media propaganda” that fuels hostilities.

There is little guarantee that the joint Saudi-UAE appeal, made following four days of talks in Jeddah, will be heeded on the ground in Aden, the scene of the worst fighting.

The dispute over southern Yemen’s future is severely straining the normally close relations between the two great Gulf monarchies, and reflects the reality that the two countries probably have always had different strategic interests in their five-year intervention in Yemen. It is not clear if the statement is intended merely to paper over continuing divisions or will lead to an end to the fighting by the respective surrogate forces.

The sudden fracture has increased the confusion in Washington’s Gulf strategy, complicating its Iran policy. In addition to forcing changes in the Trump administration’s approach to Yemen, including the possible division of the country, the split may also damage the standing of both Saudi Arabia and the UAE in Washington.

The dispute in the south started soon after UAE announced two months ago that it was unilaterally pulling most of its troops out of Yemen after more than four years of fighting, leaving its chief coalition partner, Saudi Arabia, and indigenous Yemeni government forces to continue the war against the Houthis.

In mid-August, fighters from UAE-backed southern separatist movement, the Southern Transitional Council (STC), seized power in Aden, ousting the forces backed by Saudi Arabia and led by President Abd Rabbu Mansour Hadi. Now living in exile, Hadi, who was overthrown by the Houthis in 2014, is still recognised by the UN as the legitimate ruler of Yemen. Saudi has threatened to react decisively against the STC to reinstate Hadi’s rule.

The STC, and its precursors before its May 2017 formation, have long campaigned for the restoration of South Yemen’s independence from the North, or at minimum a federal structure. The country was unified in 1990.

The eruption of fighting in the south has severely complicated UN efforts to start talks between the Houthis and the Yemen government.

The dispute means the Iranian-backed Houthis that control both Yemen’s capital Sana’a and the north of the country have found themselves under reduced military pressure.

At the same time it has become increasingly visible that the Saudis and UAE have different priorities in Yemen.

Saudi Arabia has been intent on weakening the Houthi rebels in the north, fearing an Iranian presence on its own borders joining Yemen while the UAE’s interests focus on ensuring the southern port of Aden does not come under Houthi control, thereby imperilling shipping lanes through Bab al-Mandab, upon which Emirati interests depend heavily. The dominance of the STC in the south could be enough to achieve these UAE aims, but at the expense of splitting the country in two.