(Bloomberg) -- Lithuania’s defense chief said the Baltic nation has come under an unprecedented cyber attack this week after the government announced it would start blocking the transit of sanctioned goods to the Russian exclave of Kaliningrad.

“This cyber war has been ongoing non-stop for many years,” Defense Minister Arvydas Anusauskas told LRT radio on Tuesday. “But this scale and intensity, which is perhaps not yet the highest but medium, is taking place for the first time.” 

The ministry pointed to the Russian hacker group Killnet as the source of a wave of so-called distributed denial-of-service attacks against state institutions and businesses in the nation of 2.8 million. Anusauskas said the group, which he said has ties with the Russian government, had taken responsibility and called on others to join the campaign. 

The Kremlin, which has repeatedly denied that it conducts such campaigns, had no immediate response to the Lithuanian cyber attack. 

Killnet has been blamed for similar DDoS attacks, which attempt to overload systems by flooding the target with superfluous requests from multiple sources, on institutions in the US, Estonia, Poland, the Czech Republic and other NATO countries. 

Russian President Vladimir Putin’s government has said it will retaliate against the EU member state for blocking rail transport of goods such as steel in accordance with the bloc’s sanction measures. Lithuania has accused the Kremlin of waging a propaganda campaign over the issue, saying the restrictions tied to EU measures that came into force this month involve only 1% of total transit. 

Lithuania has been able to successfully fend off the attacks, the ministry said. The cyber assault is likely to continue over the coming days, particularly in the communications, energy and finance sectors, the authorities said, warning of an increased risk of ransomware and defacement attacks. 

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