In the Horn, where cash-strapped regimes often teeter on the brink of financial survival and alliances are made and broken with bewildering regularity, the Gulf Cooperation Council (GCC) has found willing partners as Saudi-Iranian tensions escalate.
In the commercial melting pot of Dubai, where British bankers rub shoulders with Afghan carpet sellers, you would be hard-pressed to imagine that the United Arab Emirates (UAE) is fighting a major war in Yemen that has sucked in several other Gulf states and four Horn of Africa countries.
Saudi Arabia and the UAE, two key external belligerents, have small populations and large bank accounts filled with revenue from vast oil and gas reserves. The former has made the largest financial contribution with the latter supplying most of the troops.
When they decided to intervene militarily in Yemen, in March 2015, to halt a Houthi (a Zaydi, Shiite group) rebel takeover attempt, it became apparent that they would need additional boots on the ground. Conveniently situated ports and air bases were also needed. They found willing partners in Eritrea, Djibouti, Sudan and Somalia across the Red Sea and the Gulf of Aden.
Most of Yemen, especially its second city, the port of Aden, is closer to Asmara, Djibouti, Khartoum, Mogadishu and Hargeisa than Riyadh, Doha or Dubai. At the Bab al-Mandab - the straits where the Red Sea and Gulf of Aden meet - the country is just 30km from the Eritrean and Djiboutian coastline. Geographically, Horn of Africa involvement in the war makes sense.
The other half of this equation involves the political dynamics of the Gulf states, which collectively form the GCC. The GCC is also attempting to assert itself as a grouping capable of countering a perceived Iranian encroachment. In this context, and whether justified or not, the Houthi rebellion was seen as an Iranian-backed proxy.
Follow the money
Gaining supporters for the Yemen intervention wasn't simply about military power, but was also an assertion of diplomatic strength - particularly with Sunni Arab partners such as Sudan. Regional dynamics are thus likely to provide opportunities for willing partners in the Horn. Sudan, to take one example, has a complex relationship with the Gulf, historically based on two factors.
First, the weak economy has pushed many professional Sudanese to seek employment outside the country. Saudi Arabia hosts up to 900,000 Sudanese migrant workers, the UAE 75,000 and Qatar 30,000. Since the 1989 Islamist coup in Sudan, the diaspora has become a key source of remittances, propping up the very system they were forced to leave due to a stagnant employment market and repressive political culture.
Second, due to the parlous state of the economy, Sudan is perennially searching for new financial backers. In the late 1990s and 2000s, it experienced an oil boom, relying on Chinese, Indian and Malaysian companies to fill the investment gap left by Chevron (a US oil major), which exited in 1990. The 2011 secession of South Sudan brought a sharp dip in oil revenues and exposed the limited Asian appetite in the non-oil economy.
The ideological legacy of the 1989 coup - including the new regime's refusal to show solidarity with the Gulf states by denouncing Iraq's Kuwait invasion in 1990 - brought isolation, and a close relationship with Iran. It was also a source of arms vital for fighting the war in southern Sudan.
Saudi Arabia found Sudan's Iranian links and Islamist sympathies deeply concerning and, as recently as 2014, imposed financial restrictions on its banking sector, and threatened to deport thousands of migrant workers.
A windfall for the Horn of Africa
But in late 2014 Sudan made a much-publicised shift away from Tehran, closing Iranian cultural centres in Khartoum, which it accused of spreading Shiism. When the war in Yemen started, the Saudis made an offer far in excess of what Iran was prepared to commit, with unconfirmed reports stating that Sudan received $2.2 billion in return for diplomatic and military support. Initially Khartoum made only a notional military contribution, but as Saudi and Emirati losses mounted, they asked more of the Sudanese, who in October 2015 deployed what reports estimate to be between 350 and 700 ground troops.
Eritrean, Djiboutian and Somali involvement in Yemen is more opaque. In Eritrea's case, the port of Assab is being used as an air-sea logistical hub for Saudi-Emirati operations. However, unlike Khartoum, Asmara has been silent as to whether it has deployed troops. The UN Somalia Eritrea Monitoring Group wrote in September 2015 that Eritrean troop deployments would constitute "a clear violation" of UN resolution 1907 - which imposed an arms embargo on Eritrea in 2009.
The development of Eritrean relations with Saudi Arabia also appears to have worried Ethiopia, which wants to keep its erstwhile rival diplomatically isolated.
The role of Somalia and Somaliland is even murkier. Somalia made public that it has granted permission for GCC countries to use of its airspace, but it has not confirmed reports that Somali National Army soldiers are, like the Sudanese, deployed in Yemen as mercenaries. And while Somaliland has agreed to rent out port facilities at Berbera it is unknown whether this offer has been taken up. Meanwhile, Djibouti - an established Saudi ally and host of US, French and Japanese military bases - also appears to have permitted the use of its airport infrastructure for some coalition bombing missions, despite some recent tensions in relations.
The internationalisation of the Yemen war is proving a major windfall for the Horn of Africa, providing a source of ready cash and diplomatic support for governments in the region. Their involvement illustrates how regional conflagrations can drag in multiple actors with their own varied motivations. In the meantime, the Saudi-led alliance-building with countries in the Horn is likely to increase.