Europe, US warn of terror sleeper cells as war with Iran expands

The United States and several European countries are concerned about the potential risk of Iranian sleeper cells or lone wolves being activated amid the ongoing war with the Islamic Republic of Iran. Counterterrorism experts are particularly on edge following recent Iran-linked terrorist attacks in Austin, Texas, and Toronto, Canada.

Just hours after Iran’s Supreme Leader, Ali Khamenei, was declared dead following an Israeli aerial strike, gunfire was reported at a Toronto boxing gym owned by Iranian-Canadian dissident activist and cruiserweight champion Salar Gholami.

"Seventeen live rounds were fired randomly at the gym, and it was sprayed with bullets," Golami told the Iranian opposition news outlet Iran International.

There is also growing concern about Iranian-linked terrorist attacks in Europe.

“The Iranian regime has repeatedly demonstrated in the past that it carries out its terror beyond its own borders,” German lawyer and lawmaker Marc Henrichmann said in an interview with news outlet Sueddeutsche Zeitung. This raises significant concerns among international officials regarding the potential for expanded threats, particularly in light of recent events.

Matthew Levitt, a Middle East and terrorism expert and former FBI official, echoed similar sentiments in an interview with the German news outlet TAZ.

“Iranian operations abroad are definitely part of the regime’s toolkit for responding to attacks, including war,” Levitt explained. “The regime carries out such attacks wherever it can, including in Europe."

On Thursday, the Iranian ayatollah regime threatened the European Union, stating that it would pay a price for staying largely silent on the ongoing war with Iran. Tehran has appeared disappointed that European countries are not raising vocal opposition to the U.S. and Israeli strikes against Iran.

A European report in 2024 warned that the Iranian regime was actively cooperating with criminal networks to attack, especially Israelis, Jews, and dissident Iranians across Europe.

German authorities have boosted security around Jewish schools, synagogues, and institutes amid growing concerns that Iranian-linked sleeper cells or lone wolves will attempt to carry out terrorist attacks on German soil.

“It must be assumed that Jewish institutions in public life, such as schools or synagogues, could also be considered potential targets for retaliatory measures,” The Federal Office for the Protection of the Constitution (BfV) told TAZ already on Sunday.

Israeli Ambassador to Germany, Ron Prosor, also warned of potential Iranian-linked terrorist attacks in Germany.

"I think everything is possible with these terrorists," Proser assessed. "That means we have to prepare ourselves well for it, always sleep with one eye open."

Similar concerns have been raised in the United Kingdom. London-based counterterrorism expert Roger Macmillan warned that European countries should prepare for potential smaller-scale terrorist attacks carried out by Iran-affiliated individuals who are either driven by extremism or financial rewards from Tehran.

"All they need is to send somebody 20K, 5K, 10K, and say 'go down into that crowd there, find someone, stab them on the way out.' And nowadays, if somebody offers you 10,000 pounds, you can disappear with that," Macmillan warned. "So it's an increased likelihood."

In May 2025, British authorities arrested several Iranian nationals in a foiled terrorist plot against the Israeli embassy in London.

An investigative CNN report in April 2025 revealed the ayatollah regime in Tehran was employing teen gang members in Sweden to carry out terrorist attacks against Jews and Israeli interests in the Scandinavian country.