A feud between Saudi Arabia and the United Arab Emirates across the Horn of Africa is overshadowing the weekend’s African Union summit, though most of the continent’s leaders will try to avoid taking sides, nine diplomats and experts said.

What began as a rivalry in Yemen has spread across the Red Sea into a region riven with conflicts - from war in Somalia and Sudan to rivalry between Ethiopia and Eritrea and a divided Libya.

In recent years, the UAE has become an influential player in the Horn - encompassing Sudan, Somalia, Ethiopia, Eritrea, and Djibouti primarily - through multi-billion-dollar investments, robust diplomacy and discreet military support.

Saudi Arabia has been more low-profile, but diplomats say Riyadh is building an alliance that includes Egypt, Turkey and Qatar.

“Saudi Arabia has woken up and realised that it might lose the Red Sea,” a senior African diplomat told Reuters. “They have been sleeping all along while the UAE was doing its thing in the Horn.”

Initially focused on the Red Sea and the Gulf of Aden - both crucial shipping routes- the rivalry is now reaching further inland.

“Today it is in Somalia, but it is also playing out in Sudan, Sahel and elsewhere,” the diplomat said.

COMPELLED TO CHOOSE A SIDE

While these conflicts have strong local drivers, Gulf involvement is forcing countries, regions, and even warlords to choose sides, diplomats said.

Michael Woldemariam, a Horn of Africa expert at the University of Maryland, said regional actors, including Eritrea, Djibouti, Somalia and the Sudanese Armed Forces (SAF), have grown uneasy with the UAE’s “muscular” foreign policy.

“Saudis may seek to limit or curtail the UAE in the Horn, but it remains to be seen how that will play out,” he said. “UAE has a lot of leverage across the region – it has this expeditionary military presence and dense financial linkages.”

Saudi officials say UAE activities in Yemen and the Horn threaten their national security.

Senior Emirati officials say their strategy strengthens states against extremists, while U.N. experts and Western officials argue it has sometimes fuelled conflict and empowered authoritarian leaders, charges the UAE denies.

The officials and diplomats interviewed in this story declined to be named because of the sensitivity of the matter.

AVOIDING A BRAWL BETWEEN GULF POWERS

Israel’s recognition of Somaliland’s independence bid is the starkest example so far of tensions being stoked.

Somalia has cut all ties with Abu Dhabi, accusing it of influencing Israel's recognition of Somaliland. Mogadishu has since signed a defence agreement with Qatar, while Turkey sent fighter jets to the capital in a show of force.

Tensions are also rising between African Union host Ethiopia and neighbouring Eritrea, which have been on the verge of war for months. Eritrea’s leader recently visited Saudi Arabia, a trip that analysts perceived as signalling Saudi backing.

UAE and Saudi Arabia back opposing sides in Sudan’s war, all the sources and experts interviewed said. The UAE is accused of providing logistical support to the RSF paramilitary, while states in line with Saudi Arabia largely back the SAF.

Egypt, a Saudi ally, has deployed Turkish-made drones along its border with SAF and used them to strike RSF in Sudan, security officials said.

Analysts said Ethiopia benefits from UAE support, and Reuters found this week that Ethiopia is hosting a base in western Ethiopia where RSF fighters are recruited and trained.

Ethiopia has not publicly commented on the story.

'ACTING THROUGH ALLIES AND PROXIES'

Across the region, Saudi Arabia often acts through allies and proxies rather than directly, experts said.

Woldemariam said African countries were likely to tread carefully.

“Even those actors in the Horn who were alarmed by UAE influence may be cautious about how much they want to be caught up in a brawl between these two Gulf powers,” he said.

The Horn is not the only crisis on the agenda of the AU summit.

War continues in the Democratic Republic of Congo, and al-Qaeda- and Islamic State-linked insurgencies are spreading across the Sahel region.

But those conflicts are still likely to take a back seat to the Horn.

Alex Rondos, the EU’s former special representative for the region, said the Horn had become a subsidiary arena for Middle East rivalries.

“Do the Saudis and UAE ... fully grasp the implications?” he said. “Will the Horn of Africa allow itself to be broken into pieces by these foreign rivalries and their African accomplices?”