Hackers, believed to be from Russia, on Sunday targeted government agencies in the United States, in a large-scale cyberespionage campaign, CNN reported. The US Commerce Department and the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency both confirmed the data breach to the news network.

The Commerce Department said it has asked the Cybersecurity and Infrastructure Security Agency and the Federal Bureau of Investigation to look into the data breach. The CISA, on the other hand, said that it was working closely with its agency partners on the “recently discovered activity” on government networks.

The Washington Post had reported on Sunday that Russian hackers also broke into the Treasury Department and other government agencies.

Last week, cybersecurity firm FireEye had revealed that a breach by a Russia-linked group had compromised the tools that it uses to secure clients.

An unidentified official told CNN that the two incidents were related. “These sorts of attacks leveraging trusted relationships are extraordinarily difficult to detect and defend against in real-time,” the official said. “There will no doubt be more.”

The data breach prompted the National Security Council to hold a meeting at the White House, Reuters reported. “The United States government is aware of these reports and we are taking all necessary steps to identify and remedy any possible issues related to this situation,” National Security Council Spokesperson John Ullyot was quoted as saying by the news agency.