German law enforcement officers arrested four Islamic State sympathizers who were plotting to attack U.S. installations and personnel in the country.

The four men came from Tajikistan. Identified only by their first names and the first letter of their surname (Azizjon B., Muhammadali G., Farhodshoh K., and Sunatullokh K.), they age between 24- and 32-years-old.

A fifth individual, identified as a Ravsan B. by the German publication Der Spiegel, who belonged to the same terrorist cell had been arrested last year for illegal possession of firearms. He appears to have been the leader of the terrorist cell as well as its main financer.

Tactical units from the German police conducted simultaneous dawn raids in six locations in the cities of Essen, Neuss, Siegen, and Heinsberg in which they arrested the four men.

Besides plotting to attack U.S. installations, the five terrorists were tracking people who they saw as critics of Islam and compiling an assassination target deck.

There are approximately 40,000 American troops stationed in Germany. The majority are dispersed in five major installations (Bavaria, Stuttgart, Rheinland-Pfalz, Wiesbaden, and Ansbach).

German prosecutors are charging the five men for being members of a terrorist organization.

Despite being dealt with a success of significant blows in the past year, the Islamic State remains a dangerous enemy mainly because of its appeal to small cells of fanatics who are dispersed around the world. Delta Force might have taken out Abu Bakr al-Baghdadi, the terrorist organization’s former leader, in a daring operation back in October but there are thousands of ISIS fighters and their families at large or captured in makeshift detention camps.

And some of them have returned or have been returned to their countries of origin after they were captured in the battlefields of Iraq and Syria. Most European countries are trying them for joining and fighting for ISIS. But there are some who claim that returned fighters should be reintegrated into society after they have undergone a deradicalization program.

In Germany, in the event that prosecutors can’t tie a returned fighter to a specific crime, they are set free but put in a surveillance list and monitored by the German police and intelligence services. Such an approach can prevent large-scale attacks that require lengthy and careful preparation but can’t do little in the case one of the returned fighters decides to go on a killing spree in his neighborhood, a tactic that has been on the rise in the United Kingdom and France.