The Southern Transitional Council (STC) of Yemen, a group of separatists who have largely been aligned with the internationally-recognized government of Yemen ever since it was deposed by Houthi insurgents in 2014, has marched its fighters into another province — taking more territory away from its erstwhile allies and stoking fears of a renewed civil war.

Yemen’s complex web of warring factions boils down to three major powers: the Iran-backed Houthis in the north, the STC in the south, and the Presidential Leadership Council (PLC) in between them.

The PLC, which moved its seat to the port city of Aden after the Houthis captured the national capital of Sanaa in 2014, is the government acknowledged by the international community. The STC is nominally part of the PLC — in fact, its leader Aidarous al-Zubaidi is the vice-president of the PLC.

The STC has never given up on its dream of breaking off the southern provinces of Yemen into a separate country, however. Over the past few weeks, the STC has been demonstrating just how committed it remains to this vision — and how little it thinks of the rest of the PLC leadership — by seizing control of oil-rich southern provinces.

Having already taken over most of Hadramout and Mahra provinces this month, the STC announced on Monday that its fighters were moving into the province of Abyan, where they would commence “an immediate offensive on multiple targets.”

STC military spokesman Lt. Col. Mohammed al-Naqib was vague about what those targets would be, or who is currently in control of them, but the STC’s “Southern Armed Forces” command said on social media that invading Abyan was part of “Operation Eastern Arrows,” which is nominally a campaign against al-Qaeda forces that began in the summer of 2022.

Saudi Arabia, which led an intervention of Gulf states into the Yemeni civil war in 2015, has been trying to talk the STC into backing down, but al-Zubaidi said last week that his forces would not relinquish control of the territory they have seized.

“The south today stands at a critical and existential juncture imposed by the realities of the political and military situation. The next phase will be one of intensive work to build the institutions of the future South Arabian state,” Zubaidi said, making it sound as if the southern secession would be happening sooner rather than later.

Zubaidi has also said the STC’s next target would be Sanaa, which suggests he is rallying his southern forces to fight the Houthis.

On Tuesday, the National Shield Forces (NSF) — yet another of Yemen’s many armed militias, this one allied with the PLC government — announced they were “redeploying” out of Abyan and several other provinces the STC might be interested in capturing. The fallback came even as Saudi negotiators claimed they were able to convince the STC to halt its march northward and be content with the territories it had already occupied.

United Nations Secretary-General Antonio Guterres on Wednesday called for restraint in Yemen, clearly concerned that the STC advance could reignite the dormant civil war.

“I urge all parties to exercise maximum restraint, de-escalate tensions, and resolve differences through dialogue. This includes regional stakeholders, whose constructive engagement and coordination in support of U.N. mediation efforts are essential for ensuring collective security interests,” said Guterres.

The secretary-general also criticized the Houthi insurgents for taking U.N. personnel prisoner, denying Houthi allegations that the staffers were actually spies and saboteurs.

“In recent days, Houthi de facto authorities referred three of our colleagues to a special criminal court. This referral must be rescinded. They have been charged in relation to their performance of United Nations official duties. These charges must be dropped. We must be allowed to perform our work without interference,” he said.

Guterres referenced the massive humanitarian crisis that has gripped Yemen since the Houthi insurgency began, saying that nearly two-thirds of the population currently requires humanitarian assistance.

The Houthis appear to be consolidating power in the areas they control, and possibly gearing up for renewed clashes with the PLC and/or STC. On Wednesday, Houthi security units arrested Maj. Gen. Mohammed Yahya al-Hawri, a respected military leader from the former national government, and raided his home in Sanaa.

“Analysts see the arrest as a Houthi attempt to dismantle remaining tribal and military influence of the General People’s Congress party in areas surrounding Sanaa, particularly within the strategically significant Hamdan tribe,” reported Yemen Online.

The General People’s Congress (GPC) party was the ruling party in Yemen from 1993 — only three years after the country was unified — until President Ali Abdullah Saleh stepped down in 2011.

Saleh and his loyalists formed an alliance with the Houthis after they captured Sanaa, helping the insurgents to undermine and depose the elected government he once presided over. The Houthis showed their appreciation by executing Saleh for “treason” in December 2017, and they have apparently decided the rest of Saleh’s cabal in the GPC has become a threat to their power.