The German Federal Criminal Police Office (BKA) issued a warning on Wednesday that radical Islamists were increasingly planning to target railway services in Western countries.

The sabotaging of tracks and other attacks on railway infrastructure increasingly featured prominently in the plans of terrorist groups, a BKA spokesperson told the Funke media group.

According to the source, an online forum associated with the so-called Islamic State (IS) called for attacks on Western railway lines as recently as July. The widely-publicized train accident near the Bavarian town of Bad Aibling was cited as a “desirable outcome.” Twelve people died in the incident in February 2016.

IS specifically called for “lone wolves”, who are not members of terror cells but instead act individually, to carry out such attacks because they did not require a high degree of sophistication.

The terrorist network Al-Qaida promptly followed suit in August, publishing detailed plans in a magazine for attacks on locomotives, wagons, railway stations and tracks.

“Even though there is no concrete mentioning of Germany in the magazine, such attacks are also conceivable in the German Federal Republic,” the BKA representative said.

Speaking to Xinhua, German terror expert Rolf Tophoven said the BKA warning most likely reflected a “change in the modus operandi of terrorist groups as security authorities are increasingly prepared for other types of attacks.”

Islamists were looking for new “soft goals” in response to the erection of physical barriers in pedestrianized zones following the Nice, Berlin and Barcelona terror attacks where vehicles were driven at high speed into crowds of people, according to the expert.

Ansgar Heveling, president of the German parliament’s committee for the interior, told Funke media group that he shared the BKA’s concerns.

It was undeniable that jihadi groups were looking for “new and frighteningly simple possibilities” to carry out attacks, according to Heveling.

While attacks on railways are not a novelty, the politician also noted that terror groups were no longer necessarily expecting their members to become martyrs. This marks a radical change in policy and could make it easier to recruit more followers who are unwilling to commit suicide.