The fall of the Assad regime in Syria presents the international community with a range of complex challenges. First and foremost, there’s a significant risk of an ISIS resurgence. Over the past year, there’s been an uptick of ISIS attacks every single month—not only in Iraq but in Syria as well. While the new ISIS caliph stays silent, learning from his predecessors that speaking publicly is likely to lead to his demise, thousands of ISIS fighters remain in camps and prisons run by Syrian Kurds. Therefore, should internal strife break out between the various anti-Assad forces and continue to spill over into Kurdish-controlled areas, the risks of incidents like the Hasaka prison break in 2022 will rise. Reports of fighting between the Turkish-controlled Syrian National Army (SNA) and Kurdish forces under the umbrella of the Syrian Democratic Forces (SDF) in Manbij, as well as between Hayat Tahrir al-Sham (HTS) forces and the SDF in Deir al Zour, are therefore highly concerning. Continued clashes between the various groups is all the more likely since a significant part of Syria’s remaining oil and gas resources are located in areas under Kurdish control, something no power broker in Damascus will likely accept.

Furthermore, the nature of Syria’s new political order remains unclear, particularly the future relationship between the government in Damascus and Islamist terrorist groups operating in the country. Much has been written about the separation of Abu Muhammad al-Golani from al-Qaeda in 2016 and his conciliatory statements since arriving in Damascus. However, even if the HTS leader himself intends to build an inclusive political order with respect for all religious sects and minorities, HTS is part of a collation of groups, including fighters of the Turkistan Islamic Party—a.k.a. the Turkistan Islamic Movement (ETIM))—who remain loyal to al-Qaeda and its ideology and, like HTS and al-Golani, are still sanctioned by the United Nations Security Council. The HTS leader will somehow have to accommodate these fighters, who have fought, bled and died with and for him, or risk internal strife within the coalition that he has successfully led to Damascus. Unfortunately, there are already individual reports of the new government telling male teachers only to teach males and women to teach only females in Homs, and reports of Damascus checkpoints where unrelated men and women riding together in cars are being given (for now, friendly) warnings not to do so again.

By elevating the non-sanctioned Mohammed al-Bashir to the position of interim prime minister, al-Golani opened a window for political engagement. However, given the current uncertainties, any engagement by the international community should be strictly conditional. In addition to implementing an inclusive political order with appropriate protections for women and religious and ethnic minorities,  the interim government should go beyond commitments and actually destroy the remaining stockpiles of Syria’s chemical weapons. The new regime should also tackle the burgeoning Captagon drug industry that the Assad regime set up to finance its activities in recent years.

Both the U.S. and the European Union have strong leverage over the new power brokers in Damascus. In addition to sanctions against key individuals of the Assad regime, both have levied strong and effective sectoral sanctions against Syria. These sanctions could be temporarily relieved if the interim government engages in good faith with the international community. However, the fact that the EU decided not to relieve any Syria sanctions yet demonstrates the Europeans’ continuing concerns about the country’s new rulers.

While the fall of the Assad regime is a defeat for both Russia and Iran, the weakening of Iranian and Hezbollah influence in Syria presents a clear opportunity for Lebanon. Syria was the main resupply route of Iran for the Lebanese terror group. With the fall of the regime in Damascus, Hezbollah has already announced that that its resupply route through the country has been cut. A Hezbollah weakened by its war against Israel and unable to quickly rebuild is good news for the Lebanese people. Not only has Hezbollah exploited Lebanon’s economy for decades, for the past three years, the group has also held the country’s political system in a stranglehold and prevented a new government from being established. Several attempts to elect a new Lebanese president have foundered in parliament due to Hezbollah. This worsened the political and economic crisis in the country, even before Hezbollah’s attacks on Israel since October 8, 2023. Therefore, both Lebanon and the international community should seize on Hezbollah’s current weakness to push back against its national hostage taking. They should prioritize undermining Hezbollah’s finances. A particularly valuable contribution could be to tackle the cooperation between Hezbollah, international criminal networks, and other terrorist groups along the transport routes of drugs through West Africa.  Disrupting these routes would deal a severe blow to the terror group’s finances at a time when it needs money more than ever.

To fully assess the emerging terrorism challenges emanating from the fall of the Assad regime and the rise of HTS, it is important to understand that from a global Islamist terrorist perspective, these events did not happen in a vacuum. Islamist terrorist sympathizers think that their forces were able to drive American and international forces out of Afghanistan in 2021; expel the French, the United Nations, and American and European forces out of West Africa since 2022; and now defeat Russia and Iran in Syria. From their perspective, the past three years have been ones of victory. Unfortunately, in 2025, with the end of the African Transition Mission in Somalia (ATMIS) and the scheduled withdrawal of ATMIS troops from the country, the risk grows that al-Shabaab, an al-Qaeda affiliate, will take control of Somalia. Globally, in none of the central areas of ISIS and al-Qaeda activity—Afghanistan, Africa, and the Middle East— do either of these global terrorist networks face significant military pressure.

This reduced pressure on ISIS and al-Qaeda has already had a measurable effect on domestic security in Europe. Some speak already of a new terrorist wave on the continent. Not only do European security services continue to arrest ISIS supporters that plan attacks, the latest arrest happened in Germany in the second week of December. During 2024 it also became clear that Europe is once again facing all four model terrorist attack scenarios. The attack against a theater in Moscow was a classic terrorist attack. Here, the perpetrators are recruited and trained outside of the target country and then smuggled inside it. If successful, this attack scenario has a significant impact. However, the risk of detection is equally high, and if the operation is a failure, significant resources of the terrorist group have been wasted. Guided attacks, such as the foiled ones against the Taylor Swift concerts in Vienna in August, try to minimize operational costs and risks by guiding future perpetrators that live in the target country during their attack preparation through online communication. Inspired attacks, such as the knife attack in Solingen, Germany, at the end of August, are the low-cost, low-risk alternative for terror groups. Here the terror network simply publishes its propaganda online to radicalize individuals who then act on their own but in the name of the group. Until this year, this latest attack scenario was the preferred one by ISIS. Several years ago, the terror group had already published instructional material online for the use of would-be perpetrators. Finally, unaffiliated attacks, such as the attack against the Israeli consulate in Munich, Germany in September are a side effect of this strategy.

The variety of attack scenarios observed in Europe clearly indicate a slowly increasing global terrorism threat. It will be crucial that the developing situation in Syria does not make this bad situation worse.