What a deadly offensive in Syria means for a stalled civil war

The largest offensive in years by Syrian opposition fighters against government forces has stirred fears of reigniting a civil war that has been mostly frozen for years.

The new rebel push began Wednesday in Aleppo province in northwestern Syria. On Thursday, the opposition forces advanced, capturing several new villages, according to a British-based monitoring group, the Syrian Observatory for Human Rights.

The offensive seeks to stop attacks by government forces and their Iran-backed militia allies, a rebel commander said.

Two days of fierce clashes have killed more than 150 combatants from both sides: nearly 100 from rebel groups who launched the offensive and 54 regime soldiers, according to the observatory. The group gathers information from a network of activists and others across Syria, and its numbers could not be verified independently.

In addition to those deaths, more than a dozen civilians have been killed by Syrian and Russian airstrikes, according to the White Helmets, a rescue group based in opposition areas. Russia and Iran for years have robustly helped President Bashar al-Assad's autocratic regime stave off the rebels.

Who are the rebels?

The offensive unites various rebel factions that represent the last vestiges of a once-sprawling array of opposition groups. Starting in 2011, they fought hard to oust al-Assad and, at one point, controlled large parts of the country.

The main group is Hayat Tahrir al-Sham, a faction formerly linked to the terrorist group al-Qaida. It controls most of the northwestern territory still held by opposition groups.

Several Turkish-backed rebel groups have also joined the offensive, according to commanders of the groups and the observatory.

Though they share a common enemy, the various rebel factions have often fought among themselves, undermining the cohesion they needed to challenge the Syrian military.

What are the goals of the offensive?

In a video statement announcing the offensive, Lt. Col. Hassan Abdulghany, military commander of the opposition's operations room, said the attack sought to stem Syrian airstrikes and other attacks on opposition-held territory.

"To push back their fire from our people, this operation is not a choice. It is an obligation to defend our people and their land," he said. "It has become clear to everyone that the regime militias and their allies, including the Iranian mercenaries, have declared an open war on the Syrian people."

Iran has backed the Syrian government throughout the war, sending advisers and commanders of its powerful Revolutionary Guard force to bases and front lines and backing militias with thousands of fighters to defend the government.

What does the Syrian government say?

Syrian state media reported Thursday that government forces were confronting a "large-scale terrorist attack" on villages, towns and military sites.

Since the early days of the uprising, the government has characterized all opposition as "terrorists."

The government said it was responding "in cooperation with friendly forces," without specifying who those forces were. It also claimed to have inflicted heavy losses on the rebel side.

Is this linked to the regional conflict?

While Syria has not been directly involved in the conflicts roiling the Middle East over the past year, its territory has long been a proxy battlefield for international powers.

For years, Israel has carried out deadly strikes in Syria, saying its targets are Iran-backed militants including the Lebanese group Hezbollah. Those attacks have escalated in the wake of the Oct. 7, 2023, Hamas-led attack on Israel from the Gaza Strip.

The Israeli military has said some of these strikes seek to cut off the flow of weapons and intelligence between Hezbollah and Iran. Weapons and money have long flowed from Iran across Syria's borders to Hezbollah in Lebanon.

In April, a deadly Israeli strike that hit part of the Iranian Embassy complex in Damascus, Syria, killed several senior Iranian commanders.

Iranian media reported Thursday that a commander of Iran's Revolutionary Guard was killed in the rebels' new offensive.

Who controls what in Syria?

More than a decade of civil war, proxy battles and an invasion by the Islamic State group have left Syria carved into different zones of control.

The government now controls more than 60% of the country, including most major cities. But that was not always the case.

At the height of the opposition's strength in the civil war, and after the Islamic State group overran parts of Syria, the government had lost control of most of the country.

But the tide turned in 2015 when Russia's military intervened to help Assad.

Still, large parts of the country are out of government control, including opposition-held areas in the northwest and the northeast, which is dominated by a Kurdish-led militia backed by the United States.

The opposition-controlled area of northwest Syria includes parts of Idlib and Aleppo provinces, and is home to about 5 million people. More than half of them were displaced from their homes elsewhere in Syria.

Though the Islamic State group lost its last territorial foothold in Syria in 2019, it maintains sleeper cells believed to hide out in Syria's vast desert and carry out occasional attacks on government soldiers and civilians.