All four detainees were suspected of breaking Denmark's law on terrorism while in Syria, police said. According to the Copenhagen police department, weapons and ammunition were seized during the raid, Danish Radio reported. Earlier, Copenhagen Police tweeted that they was carrying out "a coordinated effort" with the Danish Security and Intelligence Service (PET) in Copenhagen's western suburb of Ishøj.
Våben og ammo fundet hos en banderelateret#politidk#anklager
— Københavns Politi (@KobenhavnPoliti) April 7, 2016
Under Danish terrorism laws, enlistment in outlawed organizations with intent to perform terrorist attacks is punishable with up to six years in jail. On Friday, the arrested individuals will face a preliminary hearing behind ‘locked doors.' For security reasons, no details of the arrest were made public due to the ongoing investigation.
"What makes the case particularly interesting is that it shows how the police get would-be terrorists convicted in good time, even if they apparently are not in the process of planning attacks here at home," says Danish Radio's legal correspondent Trine Maria Ilsøe.
Denmark's attorney general Søren Pind welcomed the arrest and pointed out that people who have fought for Daesh in Syria or Iraq may present an acute security threat.
The majority of foreign fighters hail from Denmark's three largest cities of Copenhagen, Aarhus and Odense, all of which were reported to have a considerable extremist underground. Nearly half of those who left Denmark have some sort of criminal record, PET estimates.
The report singled out the particularly nefarious Grimhøj Mosque in Aarhus, which is believed to have contributed at least 22 foreign fighters. The mosque made international headlines in February, when a hidden camera revealed an imam calling for adulterers to be stoned. Previously, the mosque entered the limelight for pledging allegiance to Daesh and promoting Sharia law.
