Saudi Arabia launched airstrikes against Sanaa in Yemen on 26 March, and said it would commit 150,000 ground troops in support of President Abdurabu Mansour Hadi.
Military intervention by Sunni Arab states, the implicit aim of which appears to be to restore President Hadi to power in Sanaa, signifies the evolution in the Sunni-Shia regional conflict from a proxy war to one directly involving its rival sponsors.
Given their past lacklustre military performance against the Houthi, this is a high-risk operation by the Saudis and other countries potentially contributing ground troops. Failure would have consequences for domestic stability, notably in Saudi Arabia and Egypt. Intervention also carries a high risk of Iranian retaliation in the form of promoting unrest among Saudi and Bahraini Shia.
Intervention is likely to be open-ended and destabilising for the countries involved, as likely failure to achieve their political objectives and heavy casualties will provoke domestic criticism.
Yemen's president Abdurabu Mansour Hadi has asked for Arab states to assist him militarily in restoring his authority in the country. Only Saudi Arabia and Egypt are in a position to contribute significant numbers of ground forces, while other Gulf States such as Kuwait, Qatar, and the United Arab Emirates are providing offensive air support and may provide small numbers of Special Forces. This report examines the limitations and consequences of intervention by Saudi Arabia and Egypt.
From proxy war to direct involvement
The crucial aspect of Saudi Arabia's intervention in Yemen is that it represents a change from using its own proxies to fight Iran's proxies, to taking on Iran's proxies directly. This follows Iran's own increasing influence and military success in Lebanon, Syria, and now Iraq, where thousands of Islamic Revolution Guards Corps (IRGC) fighters are fighting alongside Iraqi Shia militias. The Gulf Arab sponsors of the Sunni-Shia conflict evidently now assess that their core interests, including the security of the Bab-al-Mandeb strait at the southern end of the Red Sea, are sufficiently under threat to warrant direct involvement. This mirrors the manner in which the Islamic State's advances in Iraq were deemed sufficiently threatening to Iran to require sending IRGC troops into Iraq. The involvement of the regional sponsors in the Sunni-Shia conflict is likely to escalate, and raises the risk of direct war between the rival sponsors in the three-to-five year outlook.
Pressures to intervene
Saudi Arabia probably assesses that the risk of intervening in Yemen and failing is less than the risk of non-intervention. Egypt is highly dependent on economic aid from the UAE and Saudi Arabia, and is therefore unlikely to refuse a request for sending troops to challenge the Houthi. Additionally, attacking the Houthi gives Egypt's president Abdel Fattah al-Sisi and Saudi Arabia's Al-Saud ruling family a chance to reinforce their images as protectors of Arab and Sunni Muslim interests, at a time when their legitimacy is being challenged in their own countries by militant Islamists.
Saudi Arabian ambassador to the United States Adel Al-Jubeir says his
Saudi Arabia's military intervention in Yemen in November and December 2009 against the Houthi stopped short of sustained cross-border ground operations and failed to suppress the Houthi insurgency; instead the Houthis briefly took territory inside Saudi Arabia. This contributed to the sidelining of Prince Khaled bin Sultan, the then defence minister. Although the Saudis are probably calculating on a rapid ground advance to Sanaa via Marib, a consequence of which would be to force a withdrawal of Houthi fighters from the south, the Saudis face the risk of an open-ended commitment to keep Hadi in power, and a continuing Houthi insurgency. Another failure would make a serious dent to the ambitions of the king's son, Defence Minister Mohammad bin Salman, who is seeking to promote his position in the succession and whose profile in Saudi media has been very high, in association with the airstrikes. Saudi Arabia's troops are untested in combat. Moreover, their loyalty is not assured, and elements among them are likely to harbour sympathies for Al-Qaeda, potentially causing internal security problems on their return home. However, Saudi Arabia casting itself as being directly involved in the war against Shia Iran most likely serves to enhance the domestic and regional credibility of the Al Saud family, notwithstanding the risk of military failure.
Obstacles to Egyptian intervention
Egypt's military has failed to pacify the Sinai insurgency, despite a prolonged campaign using draconian methods to suppress the jihadist presence in the peninsula. Moreover, Egypt is likely to need to keep a strategic reserve for possible military intervention in Libya, where the Islamic State and other militant groups are establishing themselves. Additionally, Egypt has had no experience in deploying forces overseas since it provided a contingent to participate in the First Gulf War. Furthermore, Egypt's military intervention in Yemen in the 1960s was disastrous, contributing to Egypt's defeat in the 1967 Six Day War against Israel, and ending with the partition of the country after the Egyptian military failed to defeat the Zaidi imamate of which the Houthis are the successors.
Impact on Iran
The Iranians are likely to assess that they need to increase their support to the Houthi, to a limited extent, and notwithstanding the geography. Yemeni airspace has been closed by Saudi Arabia, leaving sea resupply of the Houthi as the only option open to Iran. This increases the risk of interception of Iranian shipping by Arab coalition warships and potentially of incidents between Iranian and Arab warships.
The conflict in Yemen is likely to increasingly draw on Iranian resources, which are already being strained by commitments in Iraq, Syria, and Lebanon. As such, Iran is likely to feel under increased pressure to reach an accord in the P5+1 negotiations, which prevents further sanctions at the very least, in order to ensure it can continue to sponsor its proxies. Iran is also likely to retaliate by putting additional pressure on Saudi Arabia through Bahrain, where it has refrained so far from supporting Bahraini protesters and insurgents directly.
Outlook and implications
Neither the Egyptians nor the Saudis are likely to be able to defeat the Houthi and their allies in combat and establish control over the mountainous terrain in which familiarity with the ground will prove a major advantage, of which the Houthi will have. As such, this intervention carries a high risk of becoming open ended, as the Yemeni army has fragmented, and there is no political leadership capable of restoring order to the country without external support. Significant Egyptian or Saudi Arabian casualties in Yemen would be likely to stoke unrest in both countries, while outright failure, involving withdrawal without having removed the Houthi from power in Sanaa, would increase the risk to political stability in both countries. Moreover, minor naval incidents between Iranian and Saudi or Egyptian vessels off the coast of Yemen, including near Bab-al-Mandeb, are increasingly likely, raising the risk of collateral damage to shipping in transit across the straits and disruption to strategic oil cargo routes, which will have an impact on the oil market.
Iran is likely to retaliate against Saudi intervention by seeking to tie down Saudi troops elsewhere, raising terrorism risks in Bahrain, and potentially in the Eastern Province in Saudi Arabia. Saudi Arabia's direct intervention in Yemen will make it easier for Iran to justify increasing the scale of its direct intervention in Iraq and potentially Syria, which in turn risks provoking Turkey.
Aircraft on the ground in Yemen are likely to be at severe risk from airstrikes, with warehouses, power plants, and roads also being at much higher risk. There is a high risk of the Houthis seeking to pre-empt the Saudis by attempting to seize Marib and the energy fields there. There is also a high risk of incursions by the Houthi into Saudi territory in Jizan Province.