Europe | Holiday season terrorism threat assessment

• The most probable type of attack would involve a lone actor carrying out a stabbing in a crowded space; high-casualty attacks remain unlikely

Jihadists will probably be particularly intent on mounting attacks in Europe over the holiday period. We assess the threat to be most pronounced in Austria, Belgium, France, Germany and the UK. There has been a rise in jihadist attacks and plots since the war in Gaza started in October 2023. This is in addition to what tends to be a heightened threat around Christmas, which coincides with the Jewish Hanukkah festival this year.

The most probable incident would involve a crude attack by a lone actor in a crowded area, such as at or near a Christmas market or religious site. But law enforcement agencies have in the last few years successfully foiled most major plots.

Middle East conflict and religious holidays compounding threat

The conflict in the Middle East continues to motivate jihadists to mount attacks in European countries. We raised the terrorism threat level for many countries to high and severe in October 2023. Since then, there have been at least 38 jihadist-linked attacks and plots, compared to nine in the year prior, according to our data. We have seen no signs of the threat easing soon; the national and local authorities, including in the UK and Germany, have this year advised of the war having a lasting radicalising effect on individuals.

We have not seen any official messages by jihadist groups related to Christmas so far. But in recent weeks, there have been calls for attacks and propaganda images showing churches and Christmas symbols shared by Islamic State (IS) supporters online. IS has also made repeated calls for attacks on Jews and Christians this year. Hanukkah coinciding with Christmas will likely contribute to the already-heightened threat. The Israeli authorities have in recent months advised that the terrorism threat against Jewish people worsens during Jewish holidays.

Threat highest in Western Europe

The likelihood of an attack appears highest in Austria, Belgium, France, Germany and the UK. There has been a notable rise in attacks and plots in these countries since October 2023, particularly in France and Germany. This includes several foiled plots to target religious sites and Christmas markets. The German and Austrian authorities in November said they will enhance security measures around Christmas events. The police in Schleswig-Holstein on 6 November arrested a jihadist sympathiser for planning an attack on a Christmas market.

Jihadist attacks likely to be crude and low-impact

A jihadist attack would likely involve a lone actor attempting a stabbing, shooting or car-ramming in a crowded public or unsecured area. This is particularly at Christmas events and Christian or Jewish religious sites. Such attacks do not require much planning or coordination and are therefore more difficult for the authorities to detect and prevent. While jihadists have used explosives in attacks in the last decade, the authorities have thwarted most such attempts in recent years. Several of these involved police finding explosives in the suspects’ possession.

The authorities’ mitigation and surveillance measures have also foiled most major plots in the last few years. As such, most successful jihadist attacks have been crude, with few casualties. Law enforcement in most Western European countries now secure open-air venues, including Christmas markets and busy shopping streets, with bollards and barricades, to prevent car-ramming attacks. These and other security measures make mass-casualty attacks less likely – albeit still plausible.

Threat from state-linked actors higher than in previous years

State-linked acts of violence have also been on the rise in Europe over the past year or so. Both Iran and Russia have seemingly turned to criminal networks to plan attacks on their behalf. The authorities in the UK and in Nordic countries reported a rise in Iran-backed incidents in recent months, particularly against Israeli and Jewish individuals and sites. There have also been dozens of Russia-linked incidents across Europe this year, including sabotage, arson and assassinations targeting the defence sector and critical infrastructure.