A Russian cyberespionage group hacked into the emails of Danish Defense Ministry employees for two years, the country’s defense minister says.

In an interview on Sunday with the Danish paper Berlingske, Defense Minister Claus Hjort Frederiksen said the Russian hacker group ATP28 accessed department employees’ emails in 2015 and 2016. While no classified information was breached, Frederiksen characterized the hack as serious.

“It is linked to the intelligence services or central elements in the Russian government, and it is a constant battle to keep them away,” Frederiksen said in the interview.

U.S. Intelligence officials consider ATP28 ― also known as “Fancy Bear” ― to be linked to the Russian government, if not an outright agent of the Kremlin. Officials believe the same group hacked the Democratic National Committee and tried to interfere in the 2016 U.S. presidential election.

Denmark, a NATO member, is the latest in a line of nations ― including the U.S., Ukraine, Georgia and Germany ― to accuse Russian hackers of cyberespionage.

The Danish Defense Ministry confirmed to Reuters that Frederiksen was accurately quoted, but didn’t provide further details. The Kremlin didn’t respond to Reuters’ request for comment.

U.S. Army Lt. Col. Michelle Baldanza, a spokeswoman for the Department of Defense, deferred to Frederiksen’s remarks but added: “[The] DoD supports the U.S. interagency consensus that Russia has been interfering in Western democratic processes, and we have no reason to believe that Russia will discontinue such activities.”

Frederiksen had warned of the likelihood of a Russian cyberattack in January, after the Danish Defense Intelligence Service issued a 2016 national risk assessment report. Though the report did not specifically single out Russia, it indicated that Denmark was at high risk of cybercrime and a cyberattack by a “foreign government.”

The Russian government was likely to “get involved in our democratic processes” the same way it allegedly did in the U.S., Frederiksen told Berlingske earlier this year.

Frederiksen said the defense ministry must strengthen its email and other cyberprotections in response to the hacking.

This story has been updated with a comment from the U.S. Department of Defense.