The head of counterterrorism for the Netherlands has said that children of radicalized Dutch jihadis pose a serious threat for national security.

Intelligence services are monitoring more than 80 children of Dutch jihadists who are currently growing up in Islamic State territory and will likely return to the Netherlands, said counterterrorism and security director Dick Schoof on Wednesday. About half of the children were born abroad but are still Dutch citizens.

Schoof’s comments preceded the release of a Dutch intelligence report Wednesday from the General Intelligence and Security Service (AIVD). The report focused on the return of jihadists from the territories under Islamic State control.

The AIVD is watching children as young as nine years of age, Schoof said, because this is the age at which ISIS militants begin to train them in the use of weapons and in making explosives. Children of this age, both boys and girls, have been used by the jihadis to commit terrorist attacks in Iraq and Syria.

According to Schoof, these children are likely to remain heavily traumatized and conditioned by their experience with the Islamic State and constitute a future threat for the Netherlands.

Since 2011, at least 280 Dutch citizens have traveled to Iraq and Syria to join the Islamic State as fighters. So far, some 50 of them have returned to the Netherlands and another 45 have been killed. The AIVD believes that more and more Dutch jihadists will be coming back to the Netherlands in the coming months, because of the worsening for the Islamic State in Syria and Iraq.

The Dutch Public Prosecutor would like to preempt the danger by prosecuting Dutch jihadists while they are still in Syria and Iraq, and before their return to the Netherlands, said national coordinating prosecutor Ferry van Veghel Thursday.

“Given the high risk of people who come back from this area, we do not want to wait until they come back before opening criminal investigations. We want it all to start now and continue in their absence,” he said.

The Prosecutor will conduct its first hearing against 12 Dutch jihadists fighting in the Syria in March as part of an effort to bring as many Dutch ISIS terrorists to justice as possible.

Meanwhile, AIVD chief Rob Bertholee said that surveillance police, justice officials and local councils must discern where the most serious dangers lie, since it is impossible to keep constant tabs on so many people.

“It is crucial that a careful risk analysis be made of every person,” he said. “It is unnecessary, and for us impossible, to monitor everyone day and night.”

The AIVD report specified that eight security officials are dedicated to monitoring Dutch jihadis full time.

On Wednesday, officials from 20 countries met in The Hague to discuss the risks posed by jihadis returning home.

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