Every day some 35,000 threatening Tweets are sent in the Netherlands and 200 are so serious that the police take a closer look, the Volkskrant reports on Thursday.

Someone is arrested or given a warning about a threat made via social media almost on a daily basis, says Martine Vis, interim Rotterdam police chief and responsible for social media within the national force.

‘You used to have to buy an envelope and write a letter and then post it,’ she said. ‘Now you type in a couple of words and make a threat. It is very easy and it happens a lot.’

Many are teenagers but others are members of interest groups or ‘radicalised’ individuals. For example, last week two teenage girls were called in for a chat with the police after posting a tweet threatening to blow up a school chemistry lab, the Volkskrant says.

Blow up the school

The police define threatening tweets as ones which involve threats of violence against a person, building or a posession, such as ‘I’ll kill you’ or ‘I’ll blow up the school’, the Volkskrant said.

Between four and five million tweets are sent every day in the Netherlands and some 40 officers are constantly monitoring them for threats. They include experts in slang. Outside experts are also brought in to clarify definitions and words, including those in foreign languages. 

The 10 regional police forces now have a special system known as a Real Time Intelligence Center which couples tweets regarded as threats with other information such as whether or not the sender is known to the police. Once this has been established, the police decide whether or not to take action.