The website of the port of Rotterdam was targeted in a cyberattack blamed on Russia-aligned hackers last week.

Several Dutch ports including Amsterdam and Groningen also faced distributed-denial-of-service attacks, known as DDoS, according to port authorities. The port of Rotterdam received information from the Dutch National Cyber Security Center that pro-Russian groups were responsible for the attack, a spokesperson said by phone. 

Dutch news outlet RTL, which first reported the incidents, said a hacker group it called “NoName057(16)” claimed the attacks were a response to the Netherlands’s plans to buy Swiss tanks for Ukraine. Earlier this year, intelligence agencies warned the Dutch maritime infrastructure faces the threat of sabotage from Russia.  

While the port of Amsterdam’s website didn’t work for over an hour on June 6, Groningen Seaports experienced online disruption lasting two days. The ports didn’t pay any ransom to the attackers and no data was stolen, said the spokespeople. 

The attacks were carried out from Russian and Serbian IP addresses, according to information the port of Rotterdam received from its service provider, the spokesperson said. 

The National Cyber Security Center didn’t immediately respond to an email seeking comment.