The security service AIVD gave the names of four Somali nationals to the elite police anti-terror squad in connection with a planned attack, homeland security director Wil van Gemert says in the NRC.

Twelve men were arrested in several raids on Friday night and all but one man has now been released from custody.
‘It is very tiresome that more people were arrested but it could not be done any other way,’ Van Gemert is quoted as saying. There was not enough time to find out if everyone present was connected with the threat so they were all arrested, he told the paper.
The target of the attack – apparently planned for December 24 or December 25 – is still not clear. No weapons or explosives were found during the raids.