Militant Islamist fighters take part in a military parade along the streets of northern Raqqa province, June 30, 2014. REUTERS/Stringer

The Islamic State group has trained at least 400 fighters to target Europe in a wave of attacks, the Associated Press reported, citing security officials. The plan is to deploy interlocking terror cells, like the ones that struck Paris and Brussels, with orders to choose the time, place and method for maximum carnage.

It has been estimated that between 400 and 600 fighters for the group, which is also known as ISIS or ISIL, have been trained specifically for attacks outside the ISIS-held territories in Iraq and Syria, according to officials. Roughly 5,000 Europeans have gone to war-torn Syria, home to ISIS' de facto capital, Raqqa, to join the movement.

There is increasing evidence that the majority of the militants’ training is taking place in Syria, as well as in Libya and other places in North Africa, several security officials have said. French speakers connected to North Africa, France and Belgium are reportedly leading shadowy cells of fighters responsible for developing attack strategies in Europe, like the ones carried out in Brussels this week and Paris in November.

Iraqi security forces arrest suspected Islamic State group members on March 10, 2016, following an operation to retake the town of Zankura, northwest of Ramadi, in Anbar province. Getty Images

"The difference is that in 2014, some of these IS fighters were only being given a couple weeks of training," said a European security official, the AP reported. "Now the strategy has changed. Special units have been set up. The training is longer. And the objective appears to no longer be killing as many people as possible but rather to have as many terror operations as possible, so the enemy is forced to spend more money or more in manpower. It's more about the rhythm of terror operations now."

The people from the cell that carried out the grisly Paris attacks on Nov. 13 are scattered across Germany, Britain, Italy, Denmark and Sweden, and recently, a new group crossed in from Turkey, a senior Iraqi intelligence official said. Before being killed in a raid, the ringleader of the attacks claimed that he had crossed into Europe in a multinational group of 90 fighters who scattered "more or less everywhere."

ISIS has claimed responsibility for the suicide blasts in Brussels on Tuesday that claimed the lives of 31 people and wounded scores more.