Pro-Russian hackers launched a series of denial-of-service attacks Monday on several municipalities and organizations linked to a NATO summit this week in the Netherlands, the Dutch government announced.

The National Cybersecurity Center said in a statement that many of the attacks were claimed by a pro-Russian hackers’ group known as NoName057(16) �and appear to have a pro-Russian ideological motive.� It did not elaborate.

The cybersecurity center said it was investigating the attacks that flood a site with data in order to overwhelm it and knock it offline, and was in contact with �national and international partners.�

Raoul Rozestraten, a spokesman for the municipality in The Hague, the Dutch city hosting the summit Tuesday and Wednesday, said the attacks hit municipalities around the country.

�We noticed more traffic on the website of some of our service providers,� he told The Associated Press. �As of now, everything in The Hague is working normally.”

The government had launched a major security operation, named �Orange Shield,� around the NATO summit.

(AP)