Brussels – Several European capitals have issued warnings against a new strategy adopted by ISIS, which calls on its militants to relinquish traveling to Syria or Iraq and perpetrate attacks in European cities instead.

These warnings come as Europe has recently been shaken by a series of violent attacks that have been carried out by ISIS terrorists. The biggest loss of life took place in November of 2015, when at least 130 people were killed in Paris.

In March, twin suicide bombings hit Zaventem Airport and Maelbeek metro station in Brussels, killing 31 people and injuring dozens more.

At least 84 people were left dead by the Nice attack in France on July 14, when a truck driven by an ISIS lone wolf plowed through crowds during Bastille Day celebrations.

In this regard, Dutch National Coordinator for Security and Counterterrorism Dick Schoof told AP that between 60 and 80 ISIS operatives in Europe were preparing to carry out terrorist attacks.

Schoof noted that the number of “foreign terrorist fighters [from the EU]” hasn’t grown over the past six months, adding however that this “does not mean that the potential threat of those who would have traveled is diminished”.

Data received from the Dutch National Coordinator for Security and Counterterrorism (NCTV) showed that between 4,000 and 5,000 European “foreign terrorist fighters” were currently in Iraq and Syria.

Schoof added that extremists were currently very scattered due to an increase in anti-ISIS military operations in Iraq and Syria. He stressed that such military operations could very possibly lead to an increase in the number of refugees posing a danger to the European Union.

The Dutch official added that “the chance of an attack in the Netherlands is real”.

“We have seen 294 terrorist fighters go overseas in Iraq and Syria and there are still 190 over there,” he said.

“And what happened in France and Brussels and Germany could happen to us,” Schoof added.