Khartoum is now paying for the aid by fighting in Yemen. In the past several weeks, hundreds of Sudanese officers and soldiers have joined the roughly 1,000 SAF troops already fighting there. In October, Sudanese Defense Minister Awad bin Auf said , “There are 6,000 fighters from special forces, ground forces and elite troops ready to participate when requested by the leadership of the coalition. … Even if more troops and military contribution is needed, we are ready for any developments.”

Members of the Gulf Cooperation Council (GCC) have indeed provided a crucial financial lifeline for heavily sanctioned Sudan. Khartoum recently announced that officials in the Saudi capital of Riyadh had deposited $1 billion in Sudan’s central bank earlier this year. The Qataris deposited $1.22 billion shortly after Sudanese President Omar Hassan al-Bashir visited Doha last year. Additionally, the Bank of Khartoum’s three main shareholders are Dubai Islamic Bank, Abu Dhabi Islamic Bank and Sharjah Islamic Bank.

Since 1997, US-imposed sanctions on Sudan’s central bank have weakened the country’s access to global financial markets and hard currency. Ongoing conflicts between the SAF and rebel movements in Darfur and the provinces of South Kordofan and Blue Nile have drained resources and undermined investor confidence. When South Sudan seceded in 2011, Sudan lost one-third of its territory and the majority of its oil. Low oil prices have also resulted in diminished revenue. These dismal conditions have led officials in the capital of Khartoum to seek financial assistance from its Gulf Arab allies.

Saudi Arabia’s disastrous military campaign in Yemen has been a source of humiliation. In an effort to prevail against the Houthi rebels, Riyadh has reached out to Sudan and other African nations for on-the-ground support. Ultimately, Saudi Arabia’s ability to secure a commitment from the Sudan Armed Forces (SAF) must be analyzed within the context of Sudan’s domestic problems, which have left the country on the verge of total economic collapse.

In the grander geopolitical picture, the elephant in the room is Iran, who is backing the Houthi rebels.

Sudan joined Riyadh’s coalition despite having spent several years strengthening ties with Iran. In 2008, Sudanese and Iranian officials signed a military cooperation agreement, and in 2013, Iran stepped up its construction of naval and logistical bases in Port Sudan. Sudan and Iran share geopolitical objectives, and Sudan is a strategic gateway for Iran into the African continent. Iran supplies financial and military support for Sudan. The two countries' relationship has been deeply unsettling for Western, Gulf Arab and Israeli officials. (In August 2013, Riyadh barred Sudan’s Bashir from Saudi airspace when he was traveling to newly elected Iranian President Hassan Rouhani’s inauguration, forcing the plane to return to Khartoum.)

Last year, however, Sudan's relationship with Tehran took a new turn. In September 2014, Sudanese authorities closed Iranian cultural centers in Khartoum and other locations, citing Iran’s alleged efforts to spread Shiism in Sudan. In reality, Sudan’s tiny Shiite minority poses no true threat to the regime, and the closure of the cultural centers can be explained only within the context of Sudan's geopolitical pivot toward Saudi Arabia.

One month after the closures, Bashir sought to further distance Sudan from Iran, declaring that Riyadh’s negative outlook on Khartoum’s true relationship with Tehran was based on “false, fabricated and exaggerated” information. He dismissed the value of Sudanese-Iranian ties by citing Tehran’s refusal to back Khartoum when economic troubles hit Sudan following South Sudan's 2011 secession. Bashir said, “We [the Sudanese] managed to overcome that [difficult] period with distinction without getting any support from Iran, not even one cent. They only offered us promises that never materialized, and this is why we don’t consider our ties with Iran strategic.” Perhaps an earlier sign of Sudan’s pivot toward the GCC — and away from Iran — came in August 2013, when the New York Times reported Khartoum had provided Syrian rebels with Sudanese- and Chinese-manufactured weapons via Qatar.

The International Criminal Court wants to try Bashir for his alleged war crimes, so Sudan’s participation in the US-sponsored coalition has raised eyebrows among human rights activists in the West. According to Akshaya Kumar of Human Rights Watch, “[Sudanese] troops have ignored the laws of war and abused civilians with impunity [in South Kordofan and Blue Nile]. … While we don't know which units have been sent to [Yemen], what we do know is that they come from an army with an appalling pedigree.” Unquestionably, the Obama administration faces a dilemma. It has been led into a de facto military partnership with a regime it has punished by means of economic sanctions and an arms embargo for its human rights abuses, including genocide and state-sponsored terrorism.

The Saudis, of course, impose no human rights litmus test for their partners in their Yemen intervention. The truth is that SAF has years of experience combatting insurgencies, and given the refusal of some of Riyadh’s other traditional military allies to send a substantial on-the-ground force to Yemen, it was logical that the kingdom would turn to Sudan for greater manpower.

Although friction between Saudi Arabia and Sudan previously stemmed from Khartoum’s support for Hamas and the Egyptian Muslim Brotherhood, those tensions appear to be dissipating. As Saudi Arabia’s King Salman bin Abdul-Aziz Al Saud seeks to unite the Sunni Arab world behind the kingdom to counter Iranian influence, Riyadh sees Sudan as an actor in this foreign policy strategy. Indeed, Sudan — an Arab League and African Union member situated along the strategically prized Red Sea — plays a unique role in the Middle East’s geopolitical order, a factor often overlooked by analysts.

Today, Sudan’s teetering economy is on the verge of collapse and sanctions have tightened the noose on the central bank. Sudan’s leaders have thus far weathered the Arab Spring, yet high inflation, unemployment (particularly among urban youth) and poverty levels may well fuel growing opposition to the regime. This potential was underscored in September 2013 when thousands of anti-austerity protesters and security forces clashed in Khartoum, resulting in a number of deaths, injuries and arrests. In sum, regime survival is a concern for Bashir as Khartoum reaches out to the Gulf Arab states to mitigate the risks associated with the country’s worsening economic crisis.

The price Sudan pays for this financial lifeline is participation in Yemen’s escalating civil war.