Diminished support for the Syrian government from Iran, Hezbollah and Russia enabled opposition forces to take the initiative and seize new territory.
For years, President Bashar al-Assad of Syria was able to beat back opposition fighters with the help of Russia, Iran and Hezbollah. Now, with those allies weakened or distracted by their own conflicts, rebels have seized the opportunity to shift the balance of power.
The rebel fighters spent months training and preparing for a surprise offensive, but even they may not have predicted how quickly they would advance. On Saturday, the rebels said they had captured almost all of Aleppo, one of Syria’s biggest cities, and they now control a broad stretch of land in the west and northwest of the country, according to the rebels and the Syrian Observatory for Human Rights, a British-based war monitor.
The timing of the assault and its success, analysts say, reveal the vulnerabilities of Mr. al-Assad’s once formidable coalition.
The Syrian civil war started 13 years ago when peaceful anti-government protests were met with brutal crackdowns, escalating into a conflict between forces loyal to Mr. al-Assad and rebels. Over time, the combatants drew support and foreign fighters from regional and international powers.
Iran, Hezbollah and Russia all sent help to the Syrian military. Hezbollah and Iranian-backed fighters battled alongside Syrian forces, Russia and Iran sent military advisers, and Russia carried out intense airstrikes on rebel-held territory.
But today, Iran has been weakened by Israeli airstrikes, battlefield losses by its proxy forces — the so-called axis of resistance — and an economic crisis at home. Hezbollah, one of those proxy forces, has been battered and diminished after 13 months of war with Israel and the killing of its leader, Hassan Nasrallah. And Russia is now nearing the end of its third year of a war of attrition with Ukraine.
“He was able to survive the civil war because of all the assistance he got, and that’s gone,” said Joshua Landis, head of the Middle East studies program at the University of Oklahoma, said of Mr. al-Assad. “Israel has changed the balance of power in the region by going on this all-out war on the axis of resistance.”
“Now Assad is all alone,” he said.
His position was weakened even further by an apparent shift by Turkey, which is allied with many of the rebel groups and had opposed an offensive against the Syrian government.
Since the Hamas-led attack on Israel on Oct. 7, 2023, Israel has increasingly carried out airstrikes on Hezbollah, which began hitting it with rockets in support of Hamas, and Iranian fighters and infrastructure inside Syria. Hezbollah and Iranian forces either went into hiding or withdrew from Syria to fight elsewhere, said Haid Haid, a senior consulting associate fellow at Chatham House, a London-based research institute.
Russia has played perhaps the most crucial role in aiding Mr. al-Assad. Though it is still assisting his government with some airstrikes, it is entrenched in its own war in Ukraine and has pulled much of its military focus away from Syria.
Even with Hezbollah and Iran by its side since the early days of the civil war, the Syrian government still lost its grip on large swaths of territory until Russia directly intervened in 2015. Alongside Syrian warplanes and military helicopters, Russian airstrikes helped turn the tide of the war in Mr. al-Assad’s favor.
Syria’s military historically struggled at urban warfare, but during the intense years of the civil war, its own air power and Russia’s allowed Mr. al-Assad to bomb the opposition into submission.
This time, though, “the regime was so much weaker then anyone thought and Russia was almost nowhere to be seen,” said Dareen Khalifa, a senior adviser at the International Crisis Group.
Since Wednesday, Russia has carried out some airstrikes against the rebels and on opposition-held towns and cities, but they were not overwhelming, according to Mr. Haid. “We have not seen the same level of support and intensity of airstrikes that we saw previously,” he said.
In the wake of the assault on Aleppo, Moscow fired its top general in Syria, Sergei Kisel, according to two military bloggers, Rybar and Military Informant, who have ties to the Russian Ministry of Defense.
Within four days, the rebels have drastically changed the front lines of the Syrian conflict, which had remained static for more than four years. And it was events beyond Syria’s borders that set the stage.
Last week, Hezbollah agreed to a cease-fire deal with Israel. The group leading the offensive against the Syrian government, Hayat Tahrir al-Sham, a former Al Qaeda affiliate, may have decided that time was of the essence, Mr. Haid and other analysts said.
“One of the things that may have pushed them to start when they did was fear that Hezbollah might resend its fighters that withdrew from those front lines,” Mr. Haid said.
But conditions on the ground in Syria also created the crucial conditions for a successful rebel offensive.
Even with his allies embroiled in other conflicts, Mr. al-Assad seemed confident that his own front lines were not at risk. His government had withdrawn some of its forces there, while soldiers continued to staff checkpoints in government-held territory — often shaking Syrians down for bribes, according to multiple analysts.
Mr. al-Assad has also failed to produce any economic improvement, which many Syrians had expected once the government recaptured large parts of the country in recent years. He also failed to unify the country or regain support from a population alienated by years of civil war and the unrelenting violence and terror carried out by the government.
The government also continued to forcibly conscript young men into the military — soldiers who, when faced with a rapidly advancing and organized rebel offensive last week, chose to flee rather than fight.
Leaders of the Hayat Tahrir al-Sham opposition group say they were watching the geopolitical shifts around them — especially the weakening of the axis of resistance by Israel, and Russia’s invasion of Ukraine — and assessing how they could exploit these changes, Ms. Khalifa said.
“At the same time,” she said, “they have been building up their military capability over the last year and have been signaling this military offensive over the last two months.”
There were other factors for the rebels to consider as well.
Until recently, Turkey, which backs some of the rebel factions involved in the offensive but has a more complicated relationship with Hayat Tahrir al-Sham, was opposed to an offensive against the Syrian government, Ms. Khalifa said.
Turkey also hosts more Syrian refugees than any other country — over three million, according to government figures — and officials have long worried that any new violence near their southern border could set off a new wave of refugees.
But last week’s offensive signals that Turkish officials may have changed their position, Ms. Khalifa said.
“All of these things combined made it an opportune time,” she said.
Muhammad Haj Kadour, Valerie Hopkins and Ben Hubbard contributed reporting.
Raja Abdulrahim reports on the Middle East and is based in Jerusalem. More about Raja Abdulrahim
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