DUBAI – On Thursday, Saudi Arabia officially urged separatist forces supported by the United Arab Emirates to pull back from two Yemeni provinces they currently occupy. This demand raises the possibility of tension within the already delicate alliance fighting against Houthi rebels.

The announcement by Saudi Arabia’s Foreign Ministry on Christmas Day seemed designed to pressure the Southern Transitional Council, a group with longstanding support from the UAE. Meanwhile, Saudi Arabia has aligned itself with various Yemeni factions, including the National Shield Forces, in its ongoing battle against the Iran-backed Houthis, which began in 2015.

According to the Saudi Foreign Ministry, the recent actions of the separatists have “led to an unwarranted escalation, adversely affecting the interests of all segments of the Yemeni population, as well as the southern cause and the overall efforts of the coalition.”

The ministry further emphasized, “The kingdom underscores the necessity for all Yemeni factions to collaborate, exercise restraint, and refrain from actions that could jeopardize security and stability, potentially leading to unintended negative consequences.”

Saudi Arabia continues to highlight that negotiations are underway.

The Council has moved into Yemen’s governorates of Hadramout and Mahra. The Saudi statement said meditation efforts were aimed at having the Council’s forces return to “their previous positions outside of the two governorates and handover the camps in those areas” to the National Shield Forces.

“These efforts remain in progress to restore the situation to its previous statement,” the ministry added.

Those aligned with the Council have increasingly flown the flag of the flag of South Yemen, which was a separate country from 1967 to 1990. There were calls for demonstrations Thursday in Aden to support political forces wanting South Yemen to again secede from Yemen, but it wasn’t immediately clear if they would go ahead given Saudi Arabia’s announcement. Aden has been the seat of power in Yemen for forces aligned against the Houthis.

The confrontation also has put pressure on the relationship between neighboring Saudi Arabia and the UAE, which maintain close relations and are members of the OPEC oil cartel but also have vied for more intensely for influence and international business in recent years.

The Council’s moves in Yemen follow an escalation of violence in Sudan, another nation on the Red Sea, where the kingdom and the Emirates back opposing forces in an ongoing war.

It’s the latest chaos to grip war-torn Yemen

The Houthis seized Yemen’s capital, Sanaa, in September 2014 and forced the internationally recognized government into exile. Tehran denies arming the rebels, although Iranian-manufactured weaponry has been found on the battlefield and in sea shipments heading to Yemen despite a United Nations arms embargo.

A Saudi-led coalition armed with U.S. weaponry and intelligence entered the war on the side of Yemen’s exiled government in March 2015. Years of inconclusive fighting has pushed the Arab world’s poorest nation to the brink of famine.

The war has killed more than 150,000 people, including fighters and civilians, and created one of the world’s worst humanitarian disasters, killing tens of thousands more.

The Houthis launched attacks on hundreds of ships in the Red Sea corridor over the Israel-Hamas war, greatly disrupting regional shipping.

While traffic has inched up recently in the lull in attacks, many shippers continue to go around Africa via the Cape of Good Hope to avoid the Red Sea and the Gulf of Aden.

Further chaos in Yemen could again draw in the United States. The U.S. launched an intense bombing campaign targeting the rebels earlier this year that President Donald Trump halted just before his trip to the Mideast. The Biden administration also conducted strikes against the Houthis, including using America’s B-2 bombers to target what it described as underground bunkers used by the Houthis.

The Houthis meanwhile announced plans for a funeral Thursday for several of its fighters, including Maj. Gen. Zakaria Abdullah Yahya Hajar, whom analysts identified as the group’s drone and missile chief. U.S. forces reportedly targeted Hajar, who allegedly received training from expeditionary Quds Force of Iran’s paramilitary Revolutionary Guard, in a strike in March in Sanaa. The Houthis provided no information on how or when he died in the funeral announcement.

Meanwhile, the Houthis have increasingly threatened Saudi Arabia and taken dozens of workers at U.N. agencies and other aid groups as prisoners, alleging without evidence that they were spies — something fiercely denied by the U.N. and others.