Escalation in Yemen Risks Renewing Civil War and Widening Gulf Tensions

Lead

On Dec. 30, 2025, Saudi airstrikes hit the southern Yemeni port city of Mukalla, targeting an arms shipment linked to the United Arab Emirates and UAE-backed separatist forces. The strikes followed a rapid STC (Southern Transitional Council) advance this month that seized large parts of Hadramout and Mahra provinces and key oil facilities. The UAE said it would withdraw forces from Yemen, and Saudi actions have dramatically fractured a fragile stalemate, raising the risk of renewed civil fighting and wider Gulf confrontation. The escalation threatens shipping routes along the Gulf of Aden and complicates regional diplomacy among Saudi Arabia, the UAE and other Gulf states.

Key Takeaways

• On Dec. 30, 2025, Saudi Arabia conducted airstrikes on Mukalla, targeting a weapons shipment allegedly destined for UAE-backed separatists in southern Yemen.
• The UAE-backed Southern Transitional Council (STC) seized most of Hadramout and Mahra provinces in December 2025, including PetroMasila, Yemen’s largest oil company.
• The STC controls major southern ports, islands and Aden’s presidential palace; its chair, Aidarous al-Zubaidi, also serves on the Presidential Leadership Council.
• The move pits the STC against forces loyal to the internationally recognized government and the Saudi-backed Hadramout Tribal Alliance, reversing a recent reduction in violence since 2022.
• The UAE said it would withdraw forces from Yemen after the strikes; the scope and timing of that pullback remain unclear.
• Hadramout is a strategic, oil-producing province stretching from the Gulf of Aden to Saudi Arabia’s border and supplies fuel to southern Yemen.
• The disruption threatens maritime security along a key trade route linking the Red Sea, Gulf of Aden and Persian Gulf.

Background

The Yemeni conflict began in 2014 when the Iran-aligned Houthi movement advanced from Saada, capturing Sanaa and forcing the internationally recognized government into exile. In 2015, a Saudi- and UAE-led coalition intervened to restore that government, turning the uprising into a broader regional proxy contest. Over the past decade the war has fragmented authority across the country: Houthis control populous northern governorates and the capital, while a mosaic of southern actors, tribes and foreign-backed forces compete for influence in the south.

The Southern Transitional Council was formed in April 2017 as an umbrella for groups seeking independence for South Yemen, which existed as a separate state until 1990. Backed materially and politically by the UAE, the STC has built local administrative structures and control over ports and islands, giving it leverage that it has used intermittently to press demands for autonomy or secession. From 2022 until late 2025, violence in many areas had declined as belligerents settled into a tense stalemate, but the arrangement depended on uneasy cooperation among anti-Houthi partners.

Main Event

This month, STC forces advanced into Hadramout and Mahra, overtaking key installations after limited clashes with government-aligned troops and Saudi-backed tribal allies. They seized PetroMasila and other oil facilities in Hadramout, consolidating control over resources that underpin southern Yemen’s economy. STC units also took a border crossing in Mahra, strengthening control along the Oman frontier, and in Aden they occupied the presidential palace that houses the Presidential Leadership Council.

Saudi airstrikes on Dec. 30 struck Mukalla, a major Gulf of Aden port in Hadramout, with official Saudi statements saying the strikes targeted a weapons shipment linked to UAE-supported forces. Analysts and local sources described the strikes as a message aimed at curbing the STC advance and pressuring Abu Dhabi and its proxies to hold back. Hours after the strikes, the UAE announced plans to withdraw its forces from Yemen, a move that officials framed as a recalibration of their role in the conflict.

The fighting has pitted elements of the Yemeni military loyal to the internationally recognized government against STC units, while the Hadramout Tribal Alliance — supported by Saudi Arabia and which had earlier seized PetroMasila to press revenue demands — has been a key local antagonist. Saudi troop repositioning from Aden earlier in December, described by a Yemeni official as a “repositioning strategy,” altered the balance on the ground and may have created the opening for the STC’s rapid gains.

Analysis & Implications

The Mukalla strikes and the STC’s month-long campaign break the fragile equilibrium that had limited large-scale confrontations since 2022. If southern fighting intensifies, Yemen risks reverting from a complex stalemate into broader civil war, stretching already depleted government resources and worsening the humanitarian crisis. A revival of internal large-scale conflict would likely increase civilian displacement and exacerbate shortages of fuel and basic services in southern governorates dependent on Hadramout’s oil output.

Regionally, the episode exposes growing competition between Riyadh and Abu Dhabi. While both countries oppose the Houthi movement, their diverging priorities — Abu Dhabi’s investment in local southern proxies and Riyadh’s focus on border security and countering Tehran — have produced strategic friction. Saudi strikes aimed at curbing an Abu Dhabi-backed advance risk diplomatic fallout and could prompt further unilateral actions by either partner, complicating any coordinated approach to the Houthi front and maritime security.

For international shipping and trade, renewed fighting near the Gulf of Aden raises the prospect of more attacks, insurance spikes and route changes for vessels moving between the Red Sea and the Persian Gulf. Multinational navies and commercial shippers may respond with increased escorts or rerouting, elevating economic costs and creating secondary pressure on global supply chains already sensitive to Red Sea disruptions.

Comparison & Data

The table shows how control in the south has shifted rapidly in December 2025, concentrating resources and ports under STC influence. Hadramout’s oil and port infrastructure provide both economic leverage and logistical capacity that could solidify an STC bargaining position in any negotiation.

Reactions & Quotes

Officials, analysts and local actors offered swift responses that underline regional sensitivity to the developments.

“Yemen’s governance and territorial integrity is an issue that must be determined by the Yemeni parties themselves.”

UAE statement (reported by NPR)

The UAE framed its position as endorsing Yemeni-led solutions even as it announced plans to withdraw forces; the language aims to deflect direct responsibility for the rising tensions while signaling a shift in Abu Dhabi’s posture.

“The strikes were intended to halt a dangerous advance and deny a weapons flow to non-state actors.”

Saudi official (statement reported by NPR)

Saudi authorities characterized the Mukalla strikes as focused on denying an arms transfer and stabilizing front lines; this rationale reflects Riyadh’s priority of preventing weapons from shifting local balances near its borders and key shipping lanes.

Unconfirmed

• The precise contents and origin of the weapons shipment struck in Mukalla have not been independently verified beyond official Saudi claims.
• The timing, scale and operational details of the UAE force withdrawal announced after the strikes remain unclear and await confirmation from UAE or independent on-the-ground reporting.
• Whether Saudi strikes mark a temporary deterrent or the start of a sustained campaign against STC positions has not been confirmed.

Bottom Line

The December 2025 STC offensive in southern Yemen and the Saudi strikes on Mukalla mark a significant deterioration of a fragile status quo that had limited active combat since 2022. Control of Hadramout’s oil infrastructure and ports gives the STC economic and strategic leverage that can reshape negotiations, while Saudi responses underscore Riyadh’s unwillingness to tolerate arms flows or rapid territorial change near its interests.

For the region, the episode raises the probability of renewed internal conflict in Yemen and a spike in Gulf tensions between long-time partners Saudi Arabia and the UAE. International actors and maritime stakeholders should monitor port access, fuel flows and diplomatic signals closely; the coming weeks will be decisive in determining whether the situation de-escalates or slides toward broader warfare with regional spillover.

Sources

• NPR (news) — original reporting and official statements compiled Dec. 30, 2025