Russian hackers attacked three nuclear research laboratories in the United States. A group called Cold River launched a phishing campaign last summer against scientists at Brookhaven, Argonne, and Lawrence Livermore laboratories in an attempt to obtain passwords, reports Reuters.

These actions are believed to have taken place in August and September, around the time UN experts visited a nuclear power plant in Ukraine, which is still under Russian occupation. Experts intended to help prevent a potential disaster after heavy shelling in the area.

It is unclear whether the phishing attempts were successful or why the hackers tried to gain access to the labs’ systems. However, Adam Meyers, senior vice president of intelligence at cybersecurity firm CrowdStrike, told Reuters that Cold River was “involved in directly supporting the Kremlin’s information operations.”

Last year, the group leaked emails from the former head of MI-6, Britain’s foreign intelligence service. Cold River is also said to have targeted non-governmental organizations investigating war crimes. Such a campaign was reportedly launched around the time the UN commission stated that Russian forces are responsible for war crimes and human rights violations in the first days of the aggressor’s invasion of Ukraine.