The Organization for Security Cooperation in Europe (OSCE), a group that monitors the Russian-fomented Ukraine conflict, has confirmed that a breach of its network was discovered last month, ABC News reports. An investigation identified the method of attack and “some of the external communication destinations” but not the perpetrator.

This attack is seen as an extension of the ongoing Ukrainian conflict, with the war having moved to cyberspace after a major power outage in the country last December was attributed to hackers. Cybersecurity company FireEye has said a Russia-linked hack group Sandworm was responsible for the blackout, using malware BlackEnergy3.

Some sources allege the attack on OSCE was possibly conducted by hacking group Fancy Bear (a.k.a. APT28, Sofacy, and Pawn Storm), which is reportedly linked to Russian military unit GRU.

“Fancy Bear’s profile closely mirrors the strategic interests of the Russian government,” says cybersecurity firm CrowdStrike, alleging it was one of the two groups behind the Democratic National Committee breach in June.

Read more on ABC News.