Last week, a separatist militia overran Yemen’s southern port city of Aden, forcing the flight of the handful of ministers loyal to the puppet President Abd Rabbu Mansour Hadi that were still in the country.

The events have laid bare the abject failure of four years of murderous war to create anything approaching a stable US and Saudi-backed regime in the impoverished Arab country. At the same time, the takeover of Aden heightened fears in Washington that the United Arab Emirates (UAE), which armed and trained the separatist militia, may be distancing itself from the bellicose US policy in the region.

The tumultuous events have played out in the context of the mounting crisis of the Saudi-led and US-backed war that has killed tens of thousands of Yemeni civilians while leaving 80 percent of the population in need of food assistance and several million on the brink of starvation. The country is facing what is acknowledged as the world’s worst humanitarian crisis.

The divergence of interests and objectives between the two principal partners in the so-called coalition waging this war—Saudi Arabia and the UAE—have become increasingly impossible to mask. This is particularly the case in the wake of the UAE’s decision announced in June to withdraw the bulk of its military from Yemen and abandon positions it had held in the northeast and northwest of the country.

It has turned over many of its positions, as well as large quantities of arms, military vehicles and equipment, to a disparate collection of militias reportedly comprising 90,000 fighters. These militias include both the Security Belt, which is loyal to the separatist Southern Transitional Council, and the Republican Guard, headed by Tariq Saleh, the nephew of longtime dictator Ali Abdullah Saleh, who directed military campaigns against the south over the course of 20 years.

What they share in common, and with the UAE, is their lack of any support for the ostensible goal of the Saudi-led war, the restoration of the so-called legitimate government of President Hadi. This was the official justification for a war against the Houthi rebels who seized the country’s most populous areas in the north, along with the capital of Sana’a, and were marching on Aden before the Saudi-led intervention began in March 2015.

While the violent events in Aden over the past week have exposed the fraud of this so-called government, the trigger for the alleged clashes is by no means clear.

Aidarous al-Zubaidi, the leader of the Southern Transitional Council, charged that its affiliated militia, the Security Belt, had to choose between “self-defense, or surrender and accepting the liquidation of our just cause.”

The “cause” to which he refers is the recreation of the state of South Yemen, which was known before 1990 as the People’s Democratic Republic of Yemen and had been closely aligned with the Soviet Union before the turn by the Stalinist bureaucracy toward capitalist restoration and the dissolution of the USSR. Under pressure from Moscow, the South Yemeni regime united with the north. Regional tensions, however, persisted, resulting in an attempted secession and civil war in 1994.

There were also reports that an Islamist militia aligned with the US-Saudi puppet regime had killed one of the separatist commanders and that members of the presidential guard had fired on the separatists first, provoking the clash.

For its part, supporters of Hadi accused the southern militia and its patron, the UAE, of carrying out a “coup.” The militia members apparently stormed the presidential palace after taking over surrounding military bases following a call by the deputy head of the Southern Transitional Council to “topple” the Hadi regime.

This was by all accounts not a difficult task. The movement of the southern militia sent cabinet ministers loyal to Hadi rushing to a Saudi jet to be flown out of the country. The militia took control of the presidential palace as well as other government buildings and bases, together with heavy weaponry, along with the port of Aden and the city’s airport. Many of Hadi’s troops reportedly defected to the separatists.

The embassy of the Hadi regime in Washington issued a statement holding “the United Arab Emirates fully responsible for the coup perpetrated against the state in Aden.”

The Hadi regime’s interior minister, Ahmed Al-Maysary, who fled the country, acknowledged that a “successful coup destroyed what’s left of this country’s sovereignty.” He went on to condemn what he called Saudi Arabia’s “silence for four days, while our partner in the coalition is slaughtering us.”

Saudi media reported that Hadi met Sunday with his patron King Salman on Sunday. Thus far, the “legitimate” president has made no public statement concerning the ouster of his officials from their last redoubt in Yemen.

According to UN reports, the fighting in Aden killed at least 40 people, while the wounded numbered in the hundreds. The clashes have taken place in civilian neighborhoods, trapping residents in their homes.

On Monday, Crown Prince Mohammed bin Salman, Saudi Arabia’s de facto ruler, met in Mecca with his UAE counterpart, Crown Prince Sheik Mohammed bin Zayed, issuing a statement calling for “conflicting Yemeni parties to prioritize dialogue and reason for the interest of Yemen.”

Southern Transitional Council President al-Zubaidi, meanwhile, declared his continued support for the “coalition” and pledged to observe a cease-fire and participate in an as-yet-unscheduled emergency summit in Saudi Arabia on the Aden crisis. There appeared to be no commitment, however, to surrender Aden to the control of Hadi’s loyalists.

The UAE is backing the southern separatists as a means of exerting control over the coastal strip of southern Yemen, its ports and, in particular its territory along the Bab el Mandeb Strait, a strategic chokepoint for the export of oil from the Persian Gulf. Partition of the country between a south controlled by the separatists and a north controlled by the Houthis would be compatible with the UAE’s interests.

The Saudi monarchy, however, is opposed to the establishment of any regime in Yemen that it does not wholly control. It, together with Washington, has pitched the conflict in Yemen as one between Sunnis and Shia, claiming that the Houthis are a proxy force for Shia-majority Iran, even though the Zayidi religious practices of the Houthis are distinct from those of Shiism, and their grievances emerged within Yemen entirely separately from the regional conflict between Saudi Arabia and Iran.

Nonetheless, Washington views the war in Yemen through the prism of its drive toward war against Iran and its bid to forge an anti-Iranian axis centered on Saudi Arabia and the other Sunni Gulf oil sheikdoms.

The US government views the events in Aden as another indication that the UAE may be separating from this axis, creating a potential obstacle to its war drive against Tehran.

The Washington Post Monday carried a worried front-page article warning that the UAE “is breaking ranks with Washington, calling into question how reliable an ally it would be in the event of a war between the United States and Iran.”

In addition to its conflict with Saudi Arabia in Yemen and its drawdown of troops from the country, the Post pointed to the recent signing of a joint agreement between the UAE’s coast guard and Iran’s Islamic Revolutionary Guard Corps on security in the Gulf, a radical departure from Washington’s drive to totally isolate Tehran.

The UAE has likewise failed to join Washington and its regional allies in blaming the sabotage of tankers off the UAE’s coast on Iran and has not agreed to join the provocative naval escort force that the US is proposing for the Persian Gulf.

The article points out that the Emirates’ rulers are concerned that if war breaks out and Iran fires missiles at its territory, it could provoke a mass exodus of foreign workers, who account for 90 percent of the sheikdom’s population and do virtually all of the work in the UAE. It is also feared that a war would send foreign investments as well as tourism plummeting.

The increasing divergence between the UAE and Washington on Iran policy has led to concern among US military officials over whether the Emirates’ rulers would allow the Pentagon to use the strategic Al Dhafra Air Base to carry out strikes against Iran.

Meanwhile, amid the internecine strife in southern Yemen and the conflicts within Washington’s anti-Iranian axis, the brutal war against the Yemeni people, made possible by US-supplied arms and munitions, along with intelligence and logistical support, including mid-air refueling for Saudi warplanes, grinds on.

Yemen’s health ministry in Sana’a reported that a Saudi airstrike had killed at least nine civilians, including five children and two women in the northwestern province of Hajjah on Sunday. Eighteen others were wounded in the attack, many of them left in critical condition. Many of the victims were reportedly members of one family that had been forced by the war to flee their home.