(Bloomberg) -- A raging conflict threatening to further splinter Yemen is also casting a shadow over a crucial Arab alliance that has backed Donald Trump’s policy against Iran.

Clashes between forces loyal to Yemen’s internationally-recognized authorities and a southern separatist group escalated this month. The government has accused the United Arab Emirates of backing the armed rebellion, a charge denied by the Gulf state.

The escalation followed a U.A.E. decision to scale back its military presence in Yemen more than four years after joining Saudi Arabia in a war to crush Houthi rebels backed by Iran. The conflict has caused one of the world’s worst humanitarian crises.

In addition to complicating an already-struggling UN attempt to end the war, the infighting has raised questions about the strength of a Saudi-U.A.E. alliance that has been a linchpin in the Trump administration’s efforts to contain Iran.

“The Saudi-U.A.E. alliance in Yemen is at a crossroads,” said Paul Sullivan, a Middle East Expert at the National Defense University in Washington D.C. “The forces to split Yemen apart seem much greater than the forces to keep it together. There will be vituperative blame games coming around the bend. Frankly, getting involved with Yemen was a losing play to begin with.”

In a statement following an emergency meeting in Riyadh on Tuesday, the Yemeni government called on Saudi Arabia to support its efforts to restore order. Addressing the United Nations Security Council on the same day, it said the attacks wouldn’t have occurred “without the full backing” of the U.A.E.

In response, the U.A.E.’s deputy UN permanent representative denied his government’s involvement and said it would do its best to help de-escalate the conflict.

Anwar Gargash, the U.A.E. State minister for foreign affairs, said on Aug. 12 that the alliance with Saudi Arabia is a “geo-strategic fact for decades to come and the key element to achieving stability in the region.”

Yemen was divided between north and south before the two united in 1990. Southerners often complain of economic marginalization, and separatist movements fought a civil war in 1994 in an unsuccessful attempt to secede.

Stronger ties between Saudi Arabia and the U.A.E. have helped shape Middle East politics in recent years. Aside from Yemen, they’ve spearheaded an unprecedented boycott of neighboring Qatar and extended billions of dollars in support to governments cracking down on Islamist groups.

But the escalating showdown between Trump and Iran has prompted the U.A.E. to rethink its priorities to avoid a conflict that could have a devastating impact on its economy.

“There have always been differences between the Emiratis and the Saudis,” said James Dorsey, senior fellow at Singapore’s S. Rajaratnam School of International Studies and its Middle East Institute. “Those differences have become more evident with the U.A.E.’s partial withdrawal from Yemen.”

A delegation from the Yemeni separatists traveled to Jeddah to take part in Saudi-brokered peace talks. The government said Wednesday it would not take part in the dialogue unless the separatists pulled out of the positions they recently captured in the south.

Martin Griffiths, the UN Yemen special envoy, told the Security Council that the fragmentation of Yemen “is becoming a stronger and more pressing threat” and that the peace process was more urgent than ever.

“There is no time to lose,” Griffiths said. “The stakes are becoming too high for the future of Yemen, the Yemeni people and indeed the wider region.”

--With assistance from Alaa Shahine and Mohammed Hatem.

To contact the reporter on this story: Glen Carey in Washington at gcarey8@bloomberg.net

To contact the editors responsible for this story: Lin Noueihed at lnoueihed@bloomberg.net, Alaa Shahine

©2019 Bloomberg L.P.