Since March, the Free Syrian Army’s (FSA) Southern Front and the al-Qaida-linked al-Nusra Front have been busy pushing back a concerted offensive by two jihadi groups long suspected of having links to the so-called Islamic State (ISIS): Liwa Shuhuda’ al-Yarmouk and Harakat al-Muthanna al-Islamiya.

Although the fighting has often been overshadowed by other developments – not least the ISIS attacks on Brussels, followed by major offensives launched elsewhere in Syria – the Daraa countryside could provide an important litmus test.

In March, fighters from Liwa Shuhuda’ al-Yarmouk (Yarmouk Martyrs’ Brigade, LSY) went on the offensive alongside Harakat al-Muthanna al-Islamiya (HMI), expanding outward from a patch of territory located between FSA-controlled territory to the north and east, as well as Syria’s borders with both Israel and Jordan to the south and west.

By late March, LSY had pushed several miles – or about halfway – into the rebel-held territory west of Daraa and Sheikh Miskeen farther north. FSA and al-Nusra Front fighters, who have been engaging with LSY since 2014, soon realized the severity of the challenge.

Speaking to Vice at the beginning of April, rebel commanders expressed regrets about not moving against LSY sooner.

Asmat al-Absi, head of the southern rebels’ supreme court, said: “The battles happening now are the price of this complacency and leniency with extremism in the south.

“That’s how we got Liwa Shuhuda’ al-Yarmouk and Harakat al-Muthanna, and if we’re complacent again, we might get new [extremist] factions coming out,” he added.

Rebel forces have recently pushed LSY and HMI back, reversing all of their gains made over the course of March and April, and even gaining additional territory.

But FSA spokesperson Issam al-Reis told Syria Deeply that this is no longer about containment.

“I don’t think there’s any plan to stop [now],” he said. “[LSY] are besieged and we’re preparing to continue our operation and finish off LSY and the rest of HMI.”

However, because of LSY’s ties to the local area through families and clans, the battle will not be easy – something that Reis acknowledged.

“If they want to fight to the end,” he said, “this will be a long battle and it will take time.”

A report in mid-April from London-based newspaper Al-Quds Al-Arabi suggested that southern rebels had been on the receiving end of more weapons from Jordan – including Grad rockets – with the purpose of eradicating LSY’s presence in southern Syria.

Elizabeth Tsurkov, a research fellow at the Tel Aviv-based Forum for Regional Thinking, who focuses on Syria, suggested reinforcements would be “a motivation in and of itself to fight, but also because [rebels] have realized that it was a mistake to let LSY start applying Sharia law” and consolidating control in the local area.

LSY: In the Shadow of ISIS

The threat posed by Liwa Shuhuda’ al-Yarmouk is not new.

The group started out under the FSA’s flag, receiving funds and assistance from the Military Operations Council (MOC), an Amman-based logistics hub supporting rebels in southern Syria and staffed by intelligence officers from 11 different countries, including the United States.

But by mid-2014 that support had ended, amid concerns over the radical direction in which LSY was heading. A handful of veterans from the Afghan jihad were known to be in LSY’s ranks.

By late 2014, some began openly accusing LSY of acting as a sleeper cell on behalf of the Islamic State group. That December, al-Nusra Front killed four of the group’s members — including Musab Ali Marfan, a powerful figure within LSY.

Obada al-Khateeb, a Daraa-based journalist and media activist, flatly described LSY’s transition. “They were with the Free Syrian Army. Now they are Da’ash,” he said, using the Arabic acronym for ISIS.

Khateeb claimed that foreign fighters from Tunisia are members of LSY, along with locals from Daraa’s surrounding countryside. He argued that some of its leadership came from the ISIS heartlands of Iraq – a possible reference to a recently appointed emir, believed to be partly behind the latest offensive.

Aymenn Jawad al-Tamimi, fellow with U.S. think-tank the Middle East Forum, has been following LSY’s development and maintains contact with figures within the group. He described the group’s “affinity with ISIS,” not only based on the telltale flag in its logo (not evidence per se), but also the group’s discourse, media strategy and style of governance.

“They’ve set up an administrative system which mimics [IS]IS’s system of diwans for various government departments. To be sure, it’s not as comprehensive as [IS]IS, but it’s a start and it’s undeniably following [IS]S’s system.” That includes a diwan al-hisba (an internal department tasked with enforcing Islamic morality) and diwan al-dawa al-masaajid (charged with the spread of Islamic faith and mosque affairs).

There have since been more concrete links established between the two groups, including the appointment of the new emir in early March – according to Tamimi, the “strongest evidence yet of links between Liwa Shuhuda’ al-Yarmouk and IS[IS].”

The new emir, Abu Abdullah al-Madani, quickly replaced his predecessor in the space of about four months, despite being relatively unknown beforehand. One of Tamimi’s sources from within LSY circles stated that “the order came from the Amir al-Mu’mineen [Commander of the Faithful],” a reference to ISIS chief Abu Bakr al-Baghdadi himself.

The Caliphate Under Strain

For some time now, reports have suggested that ISIS is on the wane, as the group struggles to hold ground it conquered during its 2014 “blitzkrieg” sweep of areas of Syria and Iraq.

While Europe was in shock from another major ISIS operation on European soil, in Brussels, more and more people began talking about how the group was on the retreat elsewhere – not least within in its self-proclaimed caliphate.

In a Washington Post report widely shared in the wake of the Brussels attacks, a senior U.S. administration official, speaking anonymously, claimed that ISIS was “collapsing town by town.” The official pointed to Shadadi, formerly an ISIS-held town in northeastern Syria, which had just been captured by Kurdish YPG forces aided by U.S. Special Forces.

“Shadadi was going to be a major six-week operation,” the official said. “The ISIS guys had dug trenches and everything. Instead, they completely collapsed. They’re collapsing town by town.”

Shortly after the fall of Shadadi, the Syrian army – supported by a constellation of pro-regime forces and heavy Russian airstrikes – retook the oasis city of Palmyra, which had been under ISIS control for months.

It was suggested that if ISIS is losing ground in Iraq and Syria it would strike out farther afield: like in Europe. However, an investigation by New York Times reporter Rukmini Callimachi later found that ISIS’s external operations in Europe had been in the pipeline for years, as early as 2014.

It may be that events in the Daraa countryside are a product of ISIS losses elsewhere in Syria, with the group attempting to push into new territory or exploit new fronts as it loses ground farther east.

“In terms of this push in [southern] Syria: Yes, you probably could tie this to there not having been much momentum and them needing to keep it by opening up a new front,” said Tamimi.

“I think IS[IS] may have seen this as a front that could be exploited. Elsewhere in Syria, they really haven’t made much progress in a long time.”