Cybersecurity at the Hanford nuclear reservation was targeted by Russian hackers as part of an ongoing cybersecurity breach of multiple U.S. agencies, according to Politico.

Department of Energy (DOE) officials in the Tri-Cities referred the Tri-City Herald’s questions about Hanford’s involvement in the breach to DOE headquarters in Washington, D.C., which did not provide any information specific to the Eastern Washington site outside Richland.

The nation is spending $2.5 billion annually on environmental cleanup of Hanford, which was used from World War II through the Cold War to produce about two-thirds of the plutonium for the nation’s nuclear-weapons program.

DOE has confirmed that it is responding to hacking that used network-management software from SolarWinds in Texas as at least one method to gain access to federal government computer systems.

DOE said Friday that the ongoing investigation has found that the malware has been isolated to its business networks only and has not impacted “mission essential national-security functions.”