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Policy Analysis

PolicyWatch 3173

Yemen’s Fragile Military Balance

Alex Almeida and Michael Knights

Also available in العربية

September 3, 2019

The latest string of roller-coaster military developments underlines the need for continued U.S. efforts to guide Saudi, Emirati, and Yemeni officials away from dangerous choices.

In less than two weeks, Yemen has witnessed the ejection of President Abdu Rabu Mansour Hadi’s forces from his provisional capital in Aden, a major southern separatist offensive into government territory, and a strong comeback by government forces. These rapid and unexpected military reverses are rich in lessons for U.S. policymakers eager to assess Hadi’s strength, the current Saudi and Emirati roles in the conflict, and the risk of an al-Qaeda recovery in Yemen.


Although the Yemen conflict has dozens of armed factions with discrete agendas, three broad camps stand out at the national level, despite their local segmentation:

  • The Houthi-led government in Sana. Rebel military networks led by the Houthi clan currently control the capital and the majority of densely populated north and central Yemen. They draw on advice and resupply from Iran and Lebanese Hezbollah.
  • The Hadi government in Aden. Underpinned by UN Security Council Resolution 2216, interim president Hadi leads the internationally recognized government, whose ministers and parliamentarians are spread across Marib, Aden, Seiyun, and other Yemeni cities, as well as Riyadh. Hadi and Vice President Ali Mohsen al-Ahmar draw on Saudi support.
  • Southern secessionists. These forces are largely gathered under the Southern Transitional Council; they also include some non-STC tribal factions from the south and east. Although they have participated in the anti-Houthi fight, they have simultaneously sought to push the Hadi government out of Aden, Hadramawt, Shabwa, and Abyan provinces. They received material and political support from the United Arab Emirates up until July, when Abu Dhabi announced that it would begin drawing down its forces in Yemen. Facing a future in which it would benefit from much less foreign help than its rivals, the STC launched a general uprising in Aden early last month, exploiting Hadi government missteps there.


Since large-scale fighting broke out between the STC and Hadi’s forces on August 7, Yemen’s remarkably fluid military situation has raced through several stages:

  • STC seizes Aden. On August 7-10, secessionist forces took over all Hadi government sites in Aden and disbanded pro-Hadi groups such as the Presidential Protection Force, completing the disintegration that had begun during a prior STC uprising in January 2018.
  • STC moves into Abyan and Shabwa. On August 20, STC forces drove 70 kilometers east along the coast into Abyan, Hadi’s home province, to take control of Zinjibar and besiege the army’s 115th Brigade at Lawdar. Local STC units and UAE-built militias also ejected Hadi forces from Ataq, the capital of the oil-rich Shabwa province located 300 kilometers further northeast.
  • Hadi launches counteroffensive. August 22-25 saw very heavy fighting in Ataq, with Hadi’s forces showing considerable defensive resilience after receiving Saudi assurances of support. The STC assault was broken on August 25, aided by fresh pro-Hadi army units and Islamist militia forces arriving from Bayhan, 200 kilometers to the northwest.
  • Hadi forces conduct pursuit operations. After quickly chasing the STC 190 kilometers southeast to Balhaf, government forces surged 350 kilometers west along the coast on August 26-28, linking up with various besieged units. Some elements bypassed Zinjibar and pushed on to Aden, where they linked up with rallying elements of the Presidential Protection Force and pro-Hadi militias. The fight for Aden then reignited, encompassing the airport and the Hadi government center at al-Maashiq Palace. Yemeni officials claim that the UAE launched airstrikes on August 29 to support pro-STC units in that fight; Abu Dhabi refutes that allegation, stating that the strikes instead targeted militants linked to al-Qaeda in the Arabian Peninsula (AQAP), who sought to exploit the chaos in Aden.

These reversals hold many lessons about Yemen’s current situation, most notably the following:

Yemeni forces are heavily reliant on foreign backers. The STC and its militia allies outnumbered Hadi’s forces in Shabwa by roughly ten brigades to seven, yet they quickly cracked when the UAE withdrew local support on August 21, cutting off their ammunition and fuel supplies. Coupled with Emirati political pressure, this lack of logistical support soon spurred three secessionist brigades to flip to Hadi without a fight. Conversely, Saudi support made Hadi’s forces more resilient, and Riyadh’s takeover of the UAE patronage system in Shabwa (i.e., paying salaries) helped flip most of the remaining secessionist brigades within four days.

The military balance can change quickly. Within two weeks, the STC went from collapsing the government presence in Aden to watching its own forces disintegrate in Shabwa and Abyan, putting Hadramawt and other secessionist strongholds under fresh military pressure. Several factors made these reversals and long-range, unopposed advances possible:

  • Newly raised STC tribal militias in Shabwa demonstrated little staying power, in contrast to resilient forces in the STC heartland of Dhale, Lahij, and Aden provinces.
  • The light, truck-mounted forces involved in many local battles can penetrate long distances very rapidly.
  • Commanders often reverse their loyalties, within hours in some cases.
  • Defeated pro-Hadi forces in Aden were never disarmed or detained, so they were able to rejoin the fight when reinforced on August 28.

Such factors underline the potential for further reversals—for instance, some STC forces could recover from their initial shock and reenter the fight, albeit only for as long as their ammunition resupply lasts.

Hadi military forces are resilient. Although ragged, the government’s local military units have demonstrated impressive defensive resilience and offensive drive throughout the past month, largely due to four factors: (1) consistent Saudi political and financial backing, (2) capable leadership from Yemen’s most famous soldiers, Ali Mohsen al-Ahmar and Mohammed al-Maqdashi, (3) the incorporation of tough Saudi-paid Islamist militias into the counteroffensive, recruited from the Islah faction and hailing from Marib, and (4) access to heavier weapons such as tanks and artillery, which the STC lacked in equivalent numbers.


The current crisis in south Yemen is not yet settled, and U.S. policymakers should stay alert for potential new shifts in the conflict, particularly the following:

Expansion opportunities for Hadi and the Houthis. President Hadi is probably not done extending his area of control, and his next target could be the export terminals of oil-rich Hadramawt province. For their part, the Houthis may see the newfound fragility of UAE-built militias as a chance for another southward thrust toward the Bab al-Mandab Strait. With Iran overtly threatening all strategic waterways in the region, the strait may look especially attractive to portions of the Houthi leadership more closely aligned with Tehran. In addition, many Hadi and allied forces have been shifted away from certain fronts to help counter the STC, leaving the government open to potential Houthi advances.

The United States and UN should therefore work to deter land grabs by both parties, which would further undermine the fragile peace process. On the Houthi side, U.S. backchannel conversations with the rebels have apparently become routine, so Washington should use them to signal Houthi leaders that any further military advances could trigger intensified American diplomatic, intelligence, and non-combat military support to the Yemeni government and its coalition allies. On Hadi’s side, the UN, Washington, and Saudi Arabia should actively discourage the government from embarking on a new offensive into Hadramawt, which would be an unprovoked military action and might not succeed as readily as the Shabwa and Abyan expeditions.

A more prominent Saudi role. After Aden fell to the STC, Saudi crown prince Muhammad bin Salman appeared to secure UAE assistance in order to collapse any broader uprising. Riyadh moved decisively, bringing visible political support, money, small-arms ammunition, and air transport assistance to the table even as its contingent of ground forces in south Yemen remained in the low hundreds. And following the crown prince’s August 12 meeting with his Emirati counterpart Muhammad bin Zayed, the UAE seemed to worked energetically to support Saudi requirements. Washington needs to recognize that Riyadh is now the address for coalition issues affecting south Yemen.

A strengthened Hadi camp. Although no one should expect him to liberate Sana anytime soon, President Hadi has retained Saudi backing, reinserted forces into Aden, captured the entirety of the Marib-Shabwa energy corridor, and positioned his forces to expand into southern Hadramawt. He has also demonstrated a keen desire to stay in office, constantly refining and strengthening his cabinet of northern and southern power players, businessmen, and technocrats. Yet while entrenching his associates at every level would be understandable for an elected leader, it is less so for a UN-installed transitional placeholder. Therefore, in addition to steering him away from a Hadramawt offensive, the UN, Washington and Riyadh should expedite discussion on transitioning beyond the interim president down the road.

Breathing space for AQAP. Al-Qaeda will likely gain from both the UAE’s declining influence and Hadi/Islah’s improved situation. Some of the Islah militias that enabled the government’s recent counteroffensive have numerous AQAP sympathizers in their ranks, and neither Hadi nor his Saudi backers have focused much on countering the terrorist group since the current war began in 2015. AQAP now enjoys an urban sanctuary in Marib city and freedom of movement in the surrounding rural tribal areas. The UAE-led, U.S.-supported campaign to counter the group in west Shabwa and Abyan may also be imperiled if the Emiratis lose influence in those provinces. While the UAE will likely leave a sizable counterterrorism force in Shabwa, its capabilities may be diminished if Saudi Arabia becomes the leading force in the province and militias continue to lose trust in Abu Dhabi. To avoid that scenario, the U.S. intelligence and defense establishments should encourage the UAE to stay fully engaged in the anti-AQAP fight, while diplomatic officials quietly press Riyadh and Hadi to ensure that the slack Saudi attitude toward combating the group does not become the new normal in Shabwa, Abyan, and Hadramawt.

Alexandre Mello is the lead security analyst at the risk advisory firm Horizon Client Access. Michael Knights is a senior fellow at The Washington Institute. Both authors have visited Yemen and the Gulf coalition states on multiple occasions to observe military operations on various fronts.