The rapid collapse of Syrian President Bashar al-Assad’s government on 8 December 2024 took almost everyone by surprise.

In just eight days, a coalition of rebels led by Hay’at Tahrir al-Sham (HTS) accomplished what had seemed out of reach for more than a decade. Exactly what US and other intelligence agencies knew or suspected in the days before the rebels’ lightening offensive will come out over time. But for now, it is clear policymakers were caught off-guard.

‘We still get surprised,’ remarked Elizabeth Richard, the US counterterrorism coordinator, at a conference in Washington. Israeli officials who have closely monitored the Syrian government for decades and carried out hundreds of airstrikes inside the country appear to have been no more prescient. Meanwhile, Kremlin spokesman Dmitry Peskov, a man hardly known for public introspection, confirmed the same for Russia. ‘Apparently events in Syria have surprised the entire world,’ he noted, adding, ‘We are not an exception.’

The revolution now underway in Syria is first and foremost an achievement for the Syrian people, and it is impossible not to share in the sense of jubilation that brought thousands of Syrians out into the streets to celebrate the fall of a brutal and hated dictator. It is likely also to be the beginning of a major reordering of the balance of power in the Middle East, a crucial arena and potential flashpoint in the global competition between the United States and its allies and a revisionist bloc centred on China, Russia, North Korea, and Iran.

Syria’s neighbours and its regional and international partners are already scrambling to understand and shape the country’s future. But if history is a guide, it will take time for the strategic implications of what’s taken place to become clear. Reflecting on why the US and others were so surprised by events in Syria may be a good place to start.

Several factors help to explain why Assad’s government unravelled so quickly. Reports suggest that the military leadership of HTS itself didn’t anticipate advancing so far or so fast. It was only when Syrian government resistance melted away in Aleppo that the group and its coalition partners realised the path was open to continue advancing towards Hama, Homs, and ultimately Damascus. Its morale and ranks depleted, the Syrian army was no longer the force that opposition groups had contended with over the previous decade. And, possibly even more importantly, Assad’s allies were weary and distracted – Russia by its war in Ukraine and Iran by Israeli attacks on its proxies in Gaza, Lebanon, and Syria itself. By the time Moscow and Tehran might have surged additional forces to reinforce Syrian military lines, it was already too late. Like Mike Campbell in Ernest Hemmingway’s The Sun Also Rises, the Syrian regime discovered that bankruptcy came ‘gradually, then suddenly.’

Strategic surprise is a perennial challenge in international politics. Scholars have long debated whether and to what extent organisational reforms to the intelligence community or advances in sensors and data analysis might help to reduce uncertainty and therefore improve governments’ ability to anticipate major events.

But there is near consensus that the main challenge often is not in the availability of information, but the assumptions, premises, and preconceptions that shape the way that information is understood and integrated with existing policy preference and concerns. As Richard Betts put it, ‘Fewer fiascos have occurred in the stages of acquisition and presentation of facts than in the stages of interpretation and response.’ The canonical case is Hitler’s invasion of the Soviet Union in June 1941, when Joseph Stalin’s conviction that an attack would be self-defeating led him to dismiss dozens of credible warnings.

In Syria, what warning signs were visible to outsiders appear to have been obscured by a grudging acceptance of the country’s de facto partition after more than a decade of fighting and an accompanying failure to comprehend how major shifts within and beyond Syria’s borders created an opportunity for HTS and its coalition partners to radically revise the fragile peace. For example, while many analysts have argued that Russia’s success stabilizing Syria after 2015 contributed to Moscow’s confidence in its plans to invade Ukraine in 2022, few if any foresaw how dramatically Russia’s military commitments in Europe would rebound to undermine its position in the Middle East.

And this is hardly the first time the United States and other governments have been taken by surprise in Syria since the outbreak of the Arab Spring.

President Obama’s 18 August 2011 statement that ‘the time has come for President Assad to step aside’ was premised on the assumption that the collapse of his government was inevitable, especially following the departures of Zine el Abidine Ben Ali in Tunisia and Hosni Mubarak in Egypt earlier that year. Indeed, in December, Frederic Hof, then the US State Department’s special envoy for Syria, testified that Assad was ‘the equivalent of a dead man walking.’ The only real question, Hof continued, was ‘how many steps remain?’

Five years – and many steps – later, Assad not only was still in power, but many experts in the United States, Europe, and the region concluded he had definitively won the war. An overly optimistic assessment in the first case gave way to an overly pessimistic one in the second, both ignoring important indicators that might have tempered these predictions.

The focus on Assad also contributed to other surprises. In the fall of 2013, for example, concerns about extremism grew sharply as the rebellion in Syria stalled and assistance intended to bolster more moderate Syrian elements proved woefully inadequate. But few if any analysts anticipated the speed and scope of the Islamic State’s blitzkrieg across western Iraq and eastern Syria the following summer, a development that decisively thrust counterterrorism to the centre of US and allied decision-making on Syria.

Similarly, US officials were initially caught off guard by the rapid build-up of aircraft, equipment, and personnel that preceded Russia’s direct intervention in Syria that began on 30 September 2015. In retrospect, the strategic logic of Russia’s actions is obvious, but at the time it was widely assumed that Moscow – which had not undertaken an expeditionary military operation since the Soviet invasion of Afghanistan in 1979 – was unlikely to take this risk. Even once Russia’s military plans became clear, the Obama administration was slow to appreciate their geopolitical significance, instead projecting onto Russia its own fears about being bogged down in yet another Middle Eastern quagmire.

What lessons does this history of repeated surprises in Syria offer for the future?

First, while there are clear winners and losers from Assad’s departure, as with any surprise it is likely to take time for the strategic implications of what’s taken place to become fully visible. There are strong incentives for multiple states, including the US, to act quickly to signal resolve and prevent bad actors from exploiting a potential power vacuum, and there is no substitute for directly engaging Syria’s new leaders to better understand and shape their plans. But Syria’s transition is likely to be long and difficult. The United States and its allies and partners would be wise to avoid rash moves and invest the labour necessary to thoroughly interrogate and revise the assumptions that have guided Syria policy for the past decade. This will be especially important for the new Trump administration, which will inherit a radically different Middle East than four years ago.

Second, the US should be careful not to over-read the latest developments. For example, Turkey will almost certainly leverage its ties to HTS and its own allies within the Syrian opposition to play a major role in establishing a government that will be friendly to Ankara. But the divisions between and among Turkey and the Gulf States that plagued earlier efforts to establish an alternative to Assad are likely to resurface.

And while Russia is down, it may not be out. Assad’s fall is a major embarrassment for Moscow, not only because he was Russia’s last client in the Middle East, but because President Putin has assigned Syria such a prominent place in his narrative of Russia’s resurgence as a major global power and reliability as an international partner.

In fact, the very Russian strategic choices in Syria that were once heralded for their shrewdness proved to be its undoing. By relying on airpower and working in partnership with Iran and Hizbollah, Russia supposedly avoided the risks and expense of a deeper commitment. This was coupled with a pragmatic diplomatic approach that privileged local ceasefires over backing Assad’s maximalist strategy to retake ‘every inch of Syrian territory.’ While most observers (including myself) assumed these arrangements would ultimately be resolved in Assad’s favour, Russia’s strategy instead enabled HTS to establish deep roots in Idlib that the group then leveraged to successfully topple the Syrian government.

The same pragmatism in international diplomacy blew up in Russia’s face. For a while, Moscow was able to present itself as the essential broker among the major players in Syria. But Russia could not shield Iran and its proxies from Israel’s sustained bombing campaign and, with Assad gone and its own military forces withdrawing, Russia has little political or military clout to resolve differences between Turkey and the Syrian Kurds.

This does not mean Russia will necessarily abandon Syria. While there are signs Russia is packing up military equipment at its facilities at Hmeimim and Tartus and relocating to eastern Libya, the US should anticipate that Moscow will seek to preserve its foothold or at least its influence in Syria – a task that will be far harder if the country’s new leaders have viable alternatives in international partners that enable them to meaningfully address the colossal tasks of rebuilding Syria’s shattered economy and infrastructure.

Finally, and more generally, essential to Assad’s defeat was the discipline and boldness that characterised the HTS-led military offensive. Analysts have rightly focused on the erosion of the Syrian military, viewing it as part of a broader pattern in which the United States has consistently overestimated the strength of its adversaries, stretching back to the Soviet Union and including not only Syria, but also Hizbollah, Iran, and Russia.

There is another, equally significant, lesson to be drawn, however. Over the past several years, the United States has consistently underestimated the determination of key actors  to upend the status quo when it conflicts with their interests and they perceive an opportunity or assess that a window may be closing. Putin’s full-scale invasion of Ukraine and Hamas’ 7 October attack in Israel were wake-up calls in this respect. Given the depth of dissatisfaction with the current international order, this kind of strategic surprise may demand the greatest attention in the months and years ahead.