Treasury says hackers accessed “certain unclassified documents” in a “major” breach, but experts believe the attack’s impacts could prove to be more significant as new details emerge.

The Cybersecurity and Infrastructure Security Agency (CISA) said Monday that there is “no indication” other federal agencies were impacted by the recent breach at the Treasury Department.

In early December 2024, the U.S. Department of the Treasury experienced a cybersecurity breach. Though China denies involvement, the breach is attributed to a Chinese state-sponsored Advanced Persistent Threat (APT) actor.

Late last month the US Treasury reported that an unspecified number of computers had been compromised by Chinese hackers following a data breach.

Ill., the top Democrat on the House select committee on China, raised concerns about the breach to Treasury Secretary Janet Yellen and asked for a meeting to discuss the situation by Jan. 15. A Treasury official told Semafor that the agency has already offered briefings to Congress.