Syria’s Civil War: The Descent Into Horror

Thirteen years after protesters in Syria first demonstrated against the four-decade rule of the Assad family, a rapid assault by rebel fighters in late 2024 succeeded in toppling one of the world’s most despotic regimes. Bashar al-Assad’s abrupt ouster and replacement by an Islamist-led transitional government has been greeted with both joy and caution.

The country’s protracted civil war saw hundreds of thousands of Syrians killed and nearly fourteen million people—more than half the prewar population—displaced. Today, Syria remains a deeply impoverished and fractured state, large parts of its territory controlled by different armed groups with varying affiliations with foreign powers. Iran, Israel, Turkey, Russia, and the United States were all drawn into the conflict either directly or indirectly over the years.

This narrative chronology explains how Syria’s civil war morphed from small acts of anti-Assad defiance to one of the deadliest and most complex wars of the twenty-first century.

Hafez al-Assad seized control from a Baathist military junta in 1970, centralizing power in the presidency. He came from the Alawi minority, a heterodox Shia sect that had long been persecuted in Syria and was elevated to privileged positions under the post–World War I French mandate. Syria has long been and remains a Sunni majority country.

In February 1982, Hafez al-Assad ordered the military to put down a Muslim Brotherhood uprising in the city of Hama with brute force. Syrian forces killed more than twenty-five thousand people there. For the regime’s opponents, Hama would become a rallying cry in 2011. For the regime, it provided Hafez’s son and successor, Bashar, with a template for responding to dissent.

The Assads presided over a system that was not just autocratic but also kleptocratic, doling out patronage to bind Syrians to the regime. As the 2011 uprising turned into civil war, many members of minority groups remained loyal to the regime, but so did some Sunnis, fearing revenge if opposition forces were to take Damascus.

Following Hafez’s death in 2000, Bashar, his thirty-five-year-old son, ran unopposed for the presidency and succeeded his father. He promised to let markets take the place of the “Arab socialism” touted by the Baathist state, upending old patronage networks. He broke up and privatized state monopolies, but the benefits were concentrated among those well connected with the regime, and the end of subsidies and price ceilings harmed rural peasants and urban laborers. A record-setting drought from 2006 to 2010 exacerbated socioeconomic problems. Mismanaged farmland was rendered fallow and farmers migrated to cities in ever-larger numbers, causing the unemployment rate to surge.

The Arab Spring began in December 2010 with the self-immolation of a Tunisian fruit vendor decrying corruption. His act prompted protests in Tunisia, and then across the Middle East and North Africa, which forced longtime strongmen in Tunisia, Egypt, and Yemen to step down. Inspired by these previously unthinkable events, fifteen boys in the southwestern city of Deraa, Syria, spray-painted on a school wall: “The people want the fall of the regime.” They were arrested and tortured. Demonstrators who rallied behind them clashed with police, and protests spread. Many protesters were calling for something more modest than regime change: the release of political prisoners, an end to the half-century state of emergency, greater freedoms, and an end to corruption. Unlike Tunisia’s Zine al-Abidine Ben Ali and Egypt’s Hosni Mubarak, Assad responded to protesters immediately, offering just token reforms while directing security services to put down the protests with force.

Anti-regime protests soon spread from Deraa to major cities such as Damascus, Hama, and Homs. Events in Deraa offered a preview of what was to come elsewhere: the Syrian army fired on unarmed protesters and carried out mass arrests, both targeting dissidents and indiscriminately sweeping up men and boys, human rights monitors reported. Torture and extrajudicial executions were frequently reported at detention centers. Then, in late April 2011, the Syrian army brought in tanks, laying siege to Deraa. The civilian death toll mounted and residents were cut off from food, water, medicine, telephones, and electricity for eleven days. Amid international condemnation, the regime offered some concessions, but it also repeated the Deraa response in other places where there were protests, at far greater length and cost, leading some regime opponents to take up arms. Local coordinating committees sprang up in villages and urban neighborhoods. Originally established to organize resistance to the regime, many of these committees took on the roles of public administration and service provision.

In July 2011, defectors from Assad’s army announced the formation of the Free Syrian Army (FSA), and soon after they began to receive shelter in Turkey. Yet the FSA, outgunned by the regime, struggled to bring its loose coalition under centralized command and control. FSA militias often didn’t coordinate their operations and sometimes had competing interests, reflecting their varied regional backers. With resources scarce, they preyed at times on the very populations they were charged with protecting. The FSA’s civilian counterpart was also established in summer 2011, in Istanbul. The Syrian National Coalition (SNC) claimed to be the government-in-exile of Syria, and the United States, Turkey, and Gulf Cooperation Council countries, among others, soon recognized it as “the legitimate representative of the Syrian people.”

But the SNC and its successor, the National Coalition, were unable to deliver significant diplomatic or material support to the opposition, and many of the regime’s opponents within Syria accorded it little legitimacy. Rival coalitions began to proliferate, and FSA fighters drifted to Islamist brigades that, with funding and arms from Gulf donors, scored greater battlefield successes against the regime.

The Assad regime’s torture and killing was exploited by al-Qaeda militants eager to capitalize on Syria’s chaos. In January 2012, a group called Jabhat al-Nusra announced itself as al-Qaeda’s Syrian franchise, and the following month al-Qaeda chief Ayman al-Zawahiri called for Sunnis from around the region to join a jihad against the regime. Jabhat al-Nusra gained Syrian and foreign recruits as it scored greater battlefield successes than rival opposition groups.

In April 2013, a separate group formed from the remnants of al-Qaeda in Iraq that called itself the Islamic State of Iraq emerged and exceeded even Jabhat al-Nusra in its brutality. In several months, its forces established control over territory spanning eastern Syria and western Iraq. The ascendance of the Islamic State and other extremist groups fed an increasingly sectarian conflict, and civilians living in the fiefs of the Islamic State—like those living under the control of the FSA and pro-regime militias—suffered abuse.

The rise of extremist groups in Syria was, in part, the regime’s doing, as Assad wanted to present to the world a stark choice between his secular rule and a jihadi alternative. In mid-2011, the regime released hundreds of Islamist militants from prisons to discredit the rebellion. They would form extremist groups such as Ahrar al-Sham, which espoused a sectarian agenda.

Both Assad’s forces and rebel groups regularly targeted civilians in areas outside their control. The deaths of some 1,400 civilians from chemical weapons deployed by the Assad regime in the summer of 2013 mobilized world powers to dismantle the regime’s chemical arsenal. However, in the following years, the Syrian government used devastating conventional arms that also caused massive civilian casualties.

The regime used sieges and aerial bombardment regularly. These collective-punishment tactics served dual purposes, analysts say: they raised the costs of resistance to civilians so that they would pressure rebels to acquiesce, and they prevented local committees from offering a viable alternative to the regime’s governance. By 2018, the UN humanitarian agency said more than one million people lived in areas that were besieged or otherwise beyond the reach of aid.

Despite a UN Security Council resolution in 2014 aimed at securing humanitarian aid routes, aid became politicized because Assad would grant UN convoys permission to distribute food and medicine in government-held areas but deny them access to rebel-held areas, and rights advocates charged the regime with targeting medical facilities and personnel [PDF]. In 2020, Syria’s ally Russia used its veto at the Security Council to allow UN aid deliveries to the rebel-held north through only one border crossing, down from four the previous year.

The deepening of Syria’s civil war made both pro- and anti-regime forces dependent on external sponsors. As major powers deepened their involvement, Syria became a battlefield on which the region’s geopolitical rivalries have been fought.

As mounting casualties and desertions weakened Assad’s army, the regime came to rely increasingly on Iran and Russia. Iran, a longtime ally interested in protecting a vital land route to its Lebanese proxy, Hezbollah, invested billions in propping up the regime. Iran’s Revolutionary Guard Corps advised Assad’s army and suffered thousands of casualties.

The Iranian volunteer Basij paramilitary force and the foreign Shia militias it has rallied saw even more casualties. Meanwhile, Russia provided Assad with critical diplomatic support. Moscow cited the 2011 NATO-led intervention in Libya and the ensuing chaos there as justification for vetoing measures in the UN Security Council that would have punished the Syrian regime. Russia then entered the conflict directly in September 2015 with the deployment of its air force (and the construction of the Khmeimim air base outside the port city of Latakia). Although Moscow claimed that its air strikes would primarily target the Islamic State and al-Qaeda, analysts said it more often targeted other rebel groups, some backed by the United States and many intermingled with al-Qaeda’s affiliate near the front lines with the regime. This helped Assad strengthen his control of population centers along the country’s western spine.

Opposition forces, too, had foreign backers. For several years, the United States covertly trained and armed rebel fighters. France and the United Kingdom provided logistical and military support. Additionally, the short-lived rapprochement by Qatar and Saudi Arabia in 2015 enabled the formation of the Army of Conquest, which comprised an array of opposition and extremist groups but effectively disbanded after several years.

Kurds have fought to consolidate a de facto autonomous territory in northern Syria, which has made them alternately friends and foes of Arab opposition groups. The Islamic State’s siege in 2014 of Kobani, a strategically located Kurdish town near the Turkish border, was a turning point. The defense of the town by the Kurdish People’s Protection Units (YPG) highlighted the militant group’s effectiveness against the Islamic State. U.S. forces aided in ousting Islamic State fighters from Kobani and continued to provide arms and air support to the YPG-led Syrian Democratic Forces (SDF).

Over time, the YPG’s priority turned to consolidating autonomous Kurdish cantons in the country’s north, a region the Kurds refer to as Rojava (Western Kurdistan). YPG fighters, interested in protecting fellow Kurds, have been accused of ethnic cleansing in mixed Arab-Kurd areas. The YPG is tied to the Turkey-based Kurdistan Workers’ Party (PKK), which Ankara and Washington have designated a terrorist organization. In August 2016, Turkey deployed its military along the Syrian border to both roll back Islamic State forces and, in tandem with Syrian Arab and Turkmen fighters, block the Kurds from linking up their two cantons in a contiguous territory. The United States faced the dilemma of trying not to alienate either the YPG or Turkey, a NATO ally that was also a vital partner in the war against the Islamic State. But Washington eventually chose Ankara, agreeing in October 2019 to remove its troops in Syria near the Turkish border so that Turkey could launch a military offensive against the Kurds.

UN-backed attempts to mediate a conflict-ending political transition in Syria have been stymied by differences among veto-wielding permanent members of the UN Security Council and other powers. Qatar, Saudi Arabia, and Turkey aligned with the United States against the Assad regime, while Iran joined Russia in backing it. Russia and China cast multiple vetoes on Syria-related Security Council resolutions, and the threat of veto deterred or watered-down humanitarian and human rights measures, reinforcing a view of the council as toothless.

A June 2012 multilateral document known as the Geneva Communiqué became the basis for one set of negotiations. It called for “a Syrian-led political process,” beginning with the establishment of a transitional governing body “formed on the basis of mutual consent.” But multiple rounds of peace talks to implement these principles yielded little. A core issue was Assad himself: he had no interest in negotiating his political demise and retained Russia’s and Iran’s backing; meanwhile, the possibility of his staying on in a transition was anathema to the opposition.

Because prospects for a negotiated settlement were dim, the United States focused on counterterrorism activities while calling for de-escalation. Meanwhile, Iran, Russia, and Turkey took the diplomatic initiative, sidelining the UN-led process and excluding the United States. Although they agreed in principle on maintaining Syria’s territorial integrity and achieving a “lasting cease-fire,” their agreements to work through their respective local allies to de-escalate the conflict failed.

More than half of Syria’s prewar population of twenty-two million has been displaced by the violence, the largest forced displacement in the world after Sudan. Almost seven million people are displaced internally and nearly the same number have fled abroad. Neighboring countries have borne the heaviest burden: Lebanon, a country of just over five million people, is hosting some 1.5 million Syrian refugees; Jordan, more than half a million; and Turkey more than three million, straining government resources. With limited work and educational opportunities, more than one million asylum seekers and refugees have journeyed to Europe, contributing to what the United Nations called the largest migrant and refugee crisis since World War II.

Disputes over how to settle refugees across the European Union (EU) posed a severe challenge to the bloc, threatening to bring an end to the Schengen system of open borders on the continent and contributing to the rise of anti-immigrant, far-right parties. The EU struck an agreement with Turkey to block refugees’ northward migration in 2016, but Turkish President Recep Tayyip Erdogan periodically threatened to permit hundreds of thousands of migrants to cross into Europe.

The regime captured the last rebel-held enclave of eastern Aleppo in December 2016 after a prolonged siege and bombardment. The city, Syria’s economic powerhouse, had been contested since 2012, and its capture marked a stark reversal of fortune for the opposition; in 2013, rebels had nearly encircled the regime-controlled western part of the city. But the campaign also demonstrated how dependent Assad had become on his foreign backers—both the Russian air force and Shiite militias—as his own forces weakened. Scores of civilians were massacred in the battle’s last days in what a UN spokesperson called “a complete meltdown of humanity.” After their defeat in Aleppo, rebels were isolated to northern Idlib Province, parts of the south, and small enclaves around Damascus and Homs.

The U.S.-led coalition, along with the Kurdish-led SDF, rolled back the Islamic State to a handful of small pockets—a small fraction of the territory it once held in an area between Iraq and Syria. By some estimates, the Islamic State in Syria shrank to a few thousand militants.

Tens of thousands of people thought to have direct or indirect links to the Islamic State were held in facilities run by the SDF. More than fifty thousand of them, the vast majority of them women and children, were crowded into the most infamous displacement camp, al-Hol.

As the threat from the Islamic State diminished, simmering rivalries took on new intensity. In early 2018, Turkish forces occupied Afrin, a predominantly Kurdish enclave in northwestern Syria. Amid the Turkish escalation, SDF fighters were diverted from the fight against the Islamic State, redeploying to Afrin.

The civil war entered a new stage in October 2019 after U.S. President Donald J. Trump removed the roughly one thousand U.S. troops supporting Kurdish fighters on the Syria-Turkey border. The surprise move cleared the way for Turkey’s Erdogan to launch a military operation there. Aiming to push Kurdish forces back to establish a twenty-mile-deep buffer zone for returned refugees, Turkish troops and their Syrian rebel allies seized towns and villages, causing hundreds of thousands of people to flee. The SDF turned to the Syrian government for help, allowing regime soldiers to reenter areas that had been held by the Kurds for years. Russian troops also entered the region to support the Syrian government.

The Turkish incursion drew international condemnation. The United States sanctioned top Turkish officials and threatened to raise tariffs on steel, but a brief cease-fire led Trump to lift the sanctions after one week, and the tariffs ultimately remained unchanged. Erdogan said his troops would not back down until they established the buffer zone in Syria.

With the assistance of their foreign backers, Assad’s forces besieged and bombarded the rebels’ final redoubts in Syria’s northwest in late 2019, imperiling hundreds of thousands of civilians. By December, the regime and its allies advanced into Idlib, where Russia-backed forces launched a devastating air campaign and clashes resumed between the regime and Turkish forces seeking to protect their opposition posts in the area. A cease-fire agreement signed by Ankara and Moscow in January quickly collapsed as regime forces captured cities along the strategically significant M5 highway, which connects Damascus and Aleppo.

Hostilities between the regime and the Turks intensified in February 2020, when Syrian government forces killed Turkish troops in direct combat for the first time, spurring Turkey to retaliate with strikes against dozens of regime targets. The fighting endangered Idlib’s population, which ballooned to three million as government authorities offered rebel fighters and civilians the choice of surrendering—risking conscription or arrest—or being bused north to the province. The heightened violence resulted in the war’s largest mass displacement to date, some nine hundred thousand people being forced from their homes. A March 2020 cease-fire agreement between Moscow and Ankara largely quelled the fighting, despite violations on both sides.

Meanwhile, the Islamic State increased its attacks [PDF] in Syria’s northeast soon after the U.S. killing of the group’s leader, Abu Bakr al-Baghdadi, in October 2019. Despite the troop drawdown announced in October, some five hundred American soldiers remained in eastern Syria to prevent the Islamic State from accessing the region’s oil fields.

A decade after the uprising that sparked the war, Syria was still mired in low-level conflict, political instability, and economic turmoil. The 2020 cease-fire stemmed violence in the Turkey-controlled northwest, while the regime maintained control of most of the rest of the country with help from Russia and Iran. At the same time, Israel increasingly began bombing targets in Syria said to belong to Iran-linked militias, including Hezbollah. A U.S. air strike targeted an Iraq-based militia in Syria just weeks after the inauguration of President Joe Biden in 2021.

Even though the violence waned, civilians suffered a deep economic crisis, with more than 90 percent of the population living in poverty. Syrians were the main victims of international sanctions, including the U.S. Caesar Act, which was meant to pressure the regime to reform but appeared to have little effect on Assad.

Diplomacy also failed to sway Assad’s government. A UN-facilitated constitution-drafting committee formed in 2019 brought together 150 representatives of civil society, the regime, and the opposition. But the onset of the COVID-19 pandemic stalled talks for months, and the committee quickly reached an impasse. As the UN-led talks foundered, the rival process led by Iran, Russia, and Turkey came no closer to resolving Syria’s political crisis. Further complicating the diplomatic field, Qatar, Russia, and Turkey began another track of negotiations on Syria’s peace process in March 2021.

Even nature refused to spare Syria—a 7.8-magnitude earthquake rocked the country’s north as well as central Turkey in February 2023. Between six and eight thousand people are believed to have been killed in Syria and more than fifty thousand in Turkey. The quake leveled thousands of buildings in Syria alone, and the United Nations estimated that at least eleven thousand Syrians lost their homes. Much of the area was the last rebel-held territory in Syria and tragically ill equipped for a natural disaster; not even half the country’s prewar health facilities remained in operation.

Affected areas under government control appeared best prepared to cope with the earthquake, with aid immediately flowing in from longtime regime allies such as Iran and Russia, as well as from Egypt, India, Iraq, and the United Arab Emirates. Winter weather and equipment shortages bogged down rescue and relief efforts directly after the disaster, which also damaged the sole remaining UN-authorized border crossing to the region from Turkey. With former al-Qaeda affiliate Hayat Tahrir al-Sham (HTS) in control of the city of Idlib, international sanctions against the Islamist group also hampered the delivery of assistance there.

Syria’s civil war took a surprising turn in late 2024 when rebel forces led by HTS launched a rapid assault that seized major regime-controlled cities, including Damascus, in a matter of days. The rebel offensive, which sent Assad fleeing to Moscow, seemed to take advantage of some seismic shifts that had weakened the regime’s core allies, namely, Hezbollah, Iran, and Russia. An Israeli campaign in southern Lebanon in late 2024 severely weakened Hezbollah leadership. Iran had also been hobbled by some recent Israeli strikes. Meanwhile, the Russian military has been focused on its grinding invasion in Ukraine.

Most Syrians and many international observers have viewed Assad’s fall with great relief, celebrating the demise of his family’s decades-long reign of fear and brutality. At the same time, many are wary of the ascendance of HTS and the potential establishment of a repressive Sunni Islamist government. Syria also remains heavily fractured and subject to the armed influence of several foreign powers and militant groups, including the Islamic State. Some of Syria’s millions of refugees are reportedly eager to return as soon as possible; many others prefer to wait and see what type of government emerges and whether it can ensure a modicum of stability and basic human rights.

Lindsay Maizland, Kali Robinson and Jonathan Masters contributed to this piece.