After about five years of what was often described as a "frozen" conflict, the front lines in Syria's 13-plus-year civil war changed dramatically over the past week.

Since 2017, when fighting began to die down, forces who oppose the regime of dictator Bashar Assad had mostly been restricted to areas in northern Syria. The regime itself controlled about 70% of the country.

But the rebels have advanced rapidly since late last week, surprising experts and observers after they launched attacks on government-held areas.

At the time of writing, rebels were moving towards the city of Homs , putting them on the verge of cutting Syrian government lines in half, separating the Assad government in the capital Damascus from coastal strongholds in Latakia and from Tartous, where a Russian naval base is located.

Human rights monitors said that by Tuesday this week, more than  700 people had been killed as a result of the renewed clashes. And for now, a final outcome is hard to predict.

But no matter what happens next, the frontlines in the Syrian civil war have shifted and are unlikely to return to their previous stalemate state. 

"The HTS and opposition advance will end sooner or later and new frontlines will firm up, but the Syrian geopolitical chessboard has been reset and all stakeholders will be looking to reposition themselves in the coming days and weeks," Charles Lister, director of the Syria program at the Washinton-based Middle East Institute, confirmed this week in his newsletter on Substack.He is referring to Hayat Tahrir al-Sham, the largest group among the rebel forces.

More mass displacement

The long-running Syrian civil war displaced about half of the country's prewar population inside the country and made between 6 and 7 million Syrians refugees outside the country. Most refugees sought shelter in neighboring countries like Turkey, Lebanon and Jordan.

This week as front lines became more volatile again, observers at the United Nations said around 120,000 people were already on the move.

"From Aleppo to Idlib to Hama, our partners report that surging hostilities are endangering civilians, driving internal displacement, disrupting the continuity of essential services and obstructing the delivery of life-saving humanitarian aid," the Danish Refugee Council said in a statement. "The UN estimates 200,000 to 400,000 Syrians could be internally displaced unless hostilities cease."

How many more will be displaced, and where they go, will depend on how rebel fighters behave in areas they now control. HTS, which believes in an Islamist political system, has reached out to minority communities and told them they have nothing to fear. Its main goal is to defeat the Assad regime, it says.

Should HTS stick to this, refugees in neighboring countries like Lebanon and Turkey, where they often face disadvantage and prejudice, may be more inclined to return to Syria.

However, should fighting escalate and rebel groups engage in abuses, a humanitarian crisis and increased migration around and out of the country is also likely. It's also possible that Assad regime supporters and soldiers will be trying to leave Syria.

Opportunity for IS extremists?

During the Syrian civil war, extremists from the group known as the "Islamic State" or IS took advantage of precarious security conditions to establish control over the central Syrian city of Raqqa.

The IS group was eventually driven out by an international coalition, led by the US, but it remains active in Syria, especially in less populated desert areas. It continues to launch attacks on all the different forces it considers its enemies — including HTS.

In 2024 the number of IS attacks in Syria has dramatically increased, the US Armed Forces' Central Command recently announced. Now both Syrian government forces and opposition fighters are distracted, fighting each other.

As Deyaa Alrwishdi, a fellow at Harvard Law School and specialist in the laws of war, pointed out this week for media outlet Just Security : "Enduring instability and weak governance are the primary factors that fuel extremist resurgences. Historically, the 'Islamic State' has exploited Syria's fragmented political landscape and power vacuums, particularly in marginalized areas." 

Assad's drug deals

The Assad regime "turned Syria into a narco-state," researchers at a New York-based security consultancy, the Soufan Center, wrote in a briefing earlier this week.

Captagon, a form of addictive methamphetamine, became an "economic lifeline" for the heavily sanctioned Syrian government, they noted, and the regime is enmeshed in a network of allied manufacturers and smugglers.

The Assad regime's drug dealing may well be impacted by renewed fighting in Syria, says Caroline Rose, director of the strategic blind spots portfolio at Washington-based think tank the New Lines Institute.

"There have been reports of Captagon being transited through these [rebel-controlled] regions especially in the early 2020s and there was evidence of illicit taxation on these goods," she told DW. "That being said, more recently HTS has definitely made an effort to start cracking down on illicit drug flows and has blamed the regime for them. It's also useful for them, a way they can demonstrate that they're taking the moral high ground."

'Regime's dramatic collapse'

After more than a decade of Syria's brutal civil war, many countries — including European nations — had more or less based their foreign policies on formerly frozen front lines.

Some countries in the region, including the United Arab Emirates and Saudi Arabia, originally supported revolutionaries in Syria and previously froze Assad out. But more recently they've been moving toward normalizing relations with him.

"Gulf capitals have come to the conclusion that the regime, with the support of Iran and Russia, was likely to wipe out the opposition," Cinzia Bianco wrote in a 2022 analysisfor Germany's Friedrich Ebert Foundation. 

Syria was allowed back to the Arab League in May 2023 as a result of this trend. The only Gulf state that is still firmly opposed to normalizing with Assad is Qatar.

But this has been upended by the emerging and volatile new front lines.

"The regime's dramatic collapse in the northwest in recent days should trigger a significant recalculation in Arab capitals," the MEI's Lister noted.

This coming Sunday, there will be an emergency meeting of Arab League foreign ministers to discuss Syria. But a unified position on the topic seems unlikely, experts say.

Edited by: Carla Bleiker