TO THE EAST of the Arabian peninsula, along the shores of the Persian Gulf, war is simmering, in the form of America’s on-again-off-again conflict with Iran. Iranian missiles have rained down on Arabian cities and infrastructure and continue to menace shipping in the Strait of Hormuz, the peninsula’s economic lifeline. But it is to the west and south, in the countries along the shores of the Red Sea and the Gulf of Aden, that fighting is really raging.

Yemen’s 12-year-old civil war is spilling beyond its borders, with rocket attacks on ships in the Red Sea and on oil terminals and airports in Saudi Arabia. On the far side of the Red Sea, the civil war in Sudan has claimed hundreds of thousands of lives and forced some 11m of the country’s 50m people from their homes. Farther south, yet another civil war, in Ethiopia, threatens to become a regional one, as forces from Eritrea join the fighting. These wars, in turn, aggravate divisions in neighbouring countries such as Libya and Somalia. It is a vast zone of devastation (see map), with destruction and killing on a scale far exceeding that of the war on Iran, or even the conflicts in Gaza or Ukraine.

The Arabian peninsula’s two biggest powers, Saudi Arabia and the United Arab Emirates, tried to avert the war in Iran, fearing—rightly, it turns out—that they would get caught in the crossfire. But instead of trying to quell the wars to their south and west, they have fuelled them, taking sides and funnelling support to favoured factions. Extraordinarily, given their similar geopolitical interests, Saudi Arabia and the UAE sometimes support opposing forces in the same conflict, intensifying and entrenching wars that were already grotesquely bloody.

Even when they are theoretically on the same side, as in Yemen, the pair often fail to co-operate, helping draw out the misery and bloodshed. Not even the existential threat posed by the war in Iran, which has throttled their oil exports and shredded America’s security umbrella, has convinced the two countries to put their differences aside. Instead, their petty rivalry is abetting the demolition of a vast region of 250m people.

The conflicts in question are vicious. In Yemen, as in Sudan, hundreds of thousands have died and millions have been displaced. The civil war in Ethiopia is on an only slightly smaller scale. All three have involved famine, massacres and other atrocities. Not all this bloodshed stems from Emirati and Saudi meddling by any stretch; all three conflicts reflect long-standing divisions within the countries concerned. Nor are the two Gulf monarchies the only meddlers: Egypt, Israel and Turkey, among others, have eagerly stuck their oars in. Yet the Saudi and especially the Emirati involvement stands out as destabilising and short-sighted.

Saudi Arabia and the UAE could scarcely have more in common. They are neighbours, sharing the same language, religion and culture. They are both wealthy, absolute monarchies whose fortunes depend on the steady export of oil and the steady military support of America. They are both trying to diversify their economies away from hydrocarbons. They both face the same geopolitical threat, a hostile Iran, and the same domestic quandary, keeping their citizens happy without democracy.

Muhammad bin Salman, the crown prince and de facto ruler of Saudi Arabia, and Muhammad bin Zayed, the emir of Abu Dhabi and president of the UAE, also have a lot in common. They are both younger siblings, not initially raised in the expectation that they would rule. They both cast themselves as modernisers, bringing development to their countries. They both fancy themselves as statesmen, wielding influence in their region and beyond.

Perhaps that is why MBS and MBZ, as they are often known, used to get on so well. In 2017, when MBS staged a palace coup at the age of 31 to become ruler of Saudi Arabia in all but name, he had help from MBZ, who had largely taken control of the UAE after his older brother, Khalifa, suffered a debilitating stroke in 2014. The Emiratis worked to promote MBS in America, where many officials had their doubts about the young, impulsive crown prince.

Diplomats described the relationship between MBZ and MBS as that of mentor and protégé, or elder and younger brother. They worked together to impose their will on the region, sending troops to Yemen in 2015 and blockading Qatar in 2017.

The mentorship did not last. Cracks began to appear in 2019, when the UAE withdrew some troops from Yemen. More disagreements followed. The Emiratis established ties with Israel in 2020, whereas the Saudis did not. In 2021 they argued over trade barriers, production quotas at the Organisation of Petroleum Exporting Countries (OPEC) and a Saudi push for firms to move their regional headquarters to Riyadh, at the expense of the Emirates.

Some of these disagreements endure. Take oil. The Saudis need prices above $90 a barrel to balance the budget and pay for costly schemes to diversify the economy. They want OPEC to impose strict production caps to keep prices high. The UAE, in contrast, can balance its budget at around $50 a barrel. It would prefer to sell more oil now, even at lower prices, lest its reserves become worthless in the future. After years of bickering about quotas, the UAE finally left OPEC in April.

Saudi Arabia’s diversification effort has also brought it into competition with the UAE. Both seek to be regional hubs for finance, trade and travel, and big forces in AI and alternative energy. The Emiratis have a decades-long head start, however, and they are keen to keep their edge.

But there is at least as much injured pride as there is substance to the royal rivalry. Saudi Arabia sees itself as the pre-eminent power among the Gulf monarchies. It is the most populous of the six, with more citizens (20m) than the other five combined and by far the biggest economy. This attitude grates on the Emiratis, who have come to see themselves as the Gulf’s real success story: their economy is more diversified, their army more professional and their society more open.

Though court politics are opaque, personal animosity appears to play a part in the Saudi-Emirati rift. Diplomats say the two rulers often go months without speaking. They make a point of avoiding each other’s capitals. MBZ skipped a summit with China’s president in Riyadh in 2022. MBS returned the snub a month later when Arab leaders gathered in Abu Dhabi. In recent years the Emirati leader has visited Azerbaijan more often than Saudi Arabia.

Perhaps the most churlish element of their competition is foreign policy. A decade ago Saudi Arabia and the UAE were allies fighting the Houthis, a Shia militia that had seized much of Yemen in 2014. They backed different factions in the anti-Houthi camp: the UAE aligned itself with separatists who seek an independent south Yemen, whereas the Saudis backed Islah, an offshoot of the Muslim Brotherhood, and tribal groupings in the north. But they managed to find common cause.

In December, though, the separatists launched an offensive against their supposed allies. The Saudis worried that they might attempt to secede. They eventually pushed the separatists back and forced the UAE to withdraw its troops from Yemen. Now they find themselves battling the Houthis without the UAE, although in recent weeks the Emiratis have hinted that they may rejoin the fight. The Houthis, meanwhile, have been advancing against their divided opponents. This week they killed more than 70 recruits to the Saudi-backed forces in a rocket attack on a training camp. They have also encircled the city of Taiz, trapping some 600,000 civilians with little food or medicine.

Even worse is the damage inflicted on Sudan, where the UAE’s adventurism and Saudi intransigence are prolonging a catastrophic conflict. The number of people killed will never be known, but reports from Darfur, an especially war-torn region, give a sense of the appalling toll. During their siege and eventual capture of the city of el-Fasher last year, the Rapid Support Forces (RSF), the militia backed by the UAE, slaughtered thousands of civilians. Fighters posted gloating videos of killings on social media. They then dumped the bodies in mass graves to cover up the scale of their crimes and began hunting the few remaining doctors in the city lest they reveal what they had seen and heard while treating survivors.

It is hard to square such horror with the Gulf countries’ stated interests in Sudan. The UAE, a rich but small country worried about its reliance on oil, sees the Horn of Africa as a potential economic hinterland. It has made investments all along the Red Sea, including in Djibouti, Egypt, Eritrea, Somalia and Somaliland. Before the war, the UAE was drawn by Sudan’s ports, precious metals and agricultural land (the UAE imports about 90% of its food).

Saudi Arabia is concerned mainly about instability in Sudan, less than 200 kilometres across the Red Sea at its closest point. It has also invested in agriculture and is keen to preserve trade through Port Sudan. The UAE’s growing role in what it considered its backyard made it nervous.

These concerns have grown more pronounced in recent months as the Iran war has disrupted trade through the Strait of Hormuz. But disagreements between the two Gulf countries shaped the war in Sudan from the very beginning. Initially both supported Abdel Fattah al-Burhan and Muhammad Hamdan Dagalo, the two generals who overthrew Sudan’s short-lived civilian government in 2021. The princes, perhaps worried that a successful democratic experiment in Sudan might give their own people ideas, seemed to prefer the military regime.

Yet when the two strongmen began fighting each other in 2023 Saudi Arabia supported the Sudanese Armed Forces (SAF), led by Mr Burhan. Meanwhile the UAE, concerned about the influence of Islamists in the ranks of the SAF, threw its weight behind Mr Dagalo’s RSF (although it does not publicly admit doing so). That turn of events was not without irony: in 2015 thousands of RSF fighters battled the Houthis in Yemen on behalf of Saudi Arabia. The Saudi payment for the deployment is thought to have helped fund the RSF’s battle against the SAF.

The conflict in Sudan might not have lasted so long were it not for the rift between the two Gulf princes. At the outbreak of the war, America and Saudi Arabia convened talks in the Saudi city of Jeddah to broker a ceasefire. Saudi diplomats, infuriated by the Emirati support for the RSF, refused to invite the UAE to the talks. After being excluded, the UAE redoubled its backing for the RSF, bringing it early successes on the battlefield and encouraging Mr Dagalo to keep fighting.

Since the beginning of the war in Iran, a similarly pernicious dynamic has played out in the other direction. The disruption to traffic in the Strait of Hormuz has sharpened Saudi Arabia’s focus on shoring up stability in the Red Sea and preventing the break-up of Sudan—an outcome that has looked increasingly possible since the RSF declared a parallel government in the Darfur region last year. The Saudi position has shifted from mediating a ceasefire between the SAF and the RSF to supporting the SAF outright, says Kholood Khair of Confluence Advisory, a Sudanese think-tank.

Saudi support has probably helped the SAF capture some territory from the RSF in recent months and may explain the army’s intransigent refusal to consider a ceasefire or even talks with the RSF.

The UAE, meanwhile, may also be helping to foment conflict in Ethiopia. A four-year-old peace agreement between the national government and rebels in the northern region of Tigray broke down in September. The rebels are thought to be getting help from Eritrea, Ethiopia’s northern neighbour, whose troops have been spotted on Ethiopian territory. Abiy Ahmed, Ethiopia’s prime minister, would like his landlocked country to regain access to the Red Sea via the ports of Eritrea (which was part of Ethiopia until 1993). There are concerns that he may use Eritrea’s incursion as a justification for an invasion, sparking a full-blown war between the two sides.

If Mr Abiy does so, it will be thanks in part to the steadfast support of the UAE. Since he came to power in 2018, it has sent billions of dollars in financial aid, investment and weapons. In September alone dozens of flights from the UAE landed in Ethiopia, thought to be carrying supplies for the campaign in Tigray.

Eritrea, meanwhile, has been trying to secure Saudi Arabia’s backing. Issaias Afwerki, Eritrea’s dictator, has held several rounds of talks with Saudi officials. The Saudis have thus far demurred. But the RSF is now being accused of using Ethiopian territory to launch attacks in Sudan. That has angered the SAF, which might back Eritrea if Ethiopia attacks, potentially merging the two wars. In contrast, if MBS and MBZ were to reconcile, they might be able to exert pressure on the warring parties to settle their differences.

An equally unfortunate dynamic appears to be in motion in Somalia. The UAE’s close ties to Somaliland, a breakaway province, and other regions run by secessionists have caused a rift with the beleaguered national government, which is courting Saudi Arabia as a counterweight. In the meantime, there are reports of strengthening links between the Houthis and the jihadists of al-Shabab, who are battling both national and provincial forces in Somalia. The Emiratis’ short-sighted factionalism, in other words, is certainly not helping to end Somalia’s civil war and may in fact be exacerbating it.

Each individual decision that embroiled the UAE and Saudi Arabia in these many conflicts and then gradually pitted them against one another may have seemed rational enough at the time. But the results clearly do not serve either country’s interests. The region on their doorstep is poorer, more unstable and more violent than when their interventions began. It presents fewer opportunities for investment and more potential for unwelcome spillovers, of refugees or violence. Their meddling generates ill-will between the pair at a time when their overriding concern should be co-operating to counter the menace of Iran. And it generates untold misery for the 250m people around whom the region’s wars are intensifying. ■