It was recently revealed that Chinese government-linked hackers breached the U.S. Treasury Department last month, though officials have insisted that only non-classified information was accessed and stolen.

Now, however, it has been further revealed that the Treasury breach involved hackers gaining access to a particularly sensitive office that reviews foreign investments in the U.S. for any possible national security risks, CNN reported.

That office is the Cabinet-level Committee on Foreign Investments in the United States, or CFIUS, which has the authority to approve or deny proposed business investments and real estate purchases by foreign companies and governments, such as China or communist regime-linked entities.

Chinese hackers breached CFIUS

According to CNN, at least three unnamed U.S. officials have confirmed that Chinese hackers breached CFIUS as part of the broader hack of the Treasury Department last month -- a breach that had not been previously disclosed.

Ironically, the breach occurred in the same month that CFIUS was granted increased authority to review and act upon proposed Chinese purchasers of large plots of real estate near U.S. military bases, which obviously raises legitimate concerns about the potential for espionage or sabotage.

When questioned about this latest revelation of the extent of the Chinese hack of the Treasury Department, a spokesperson declined to confirm or deny the reports and instead referenced an initial statement about the broader breach.

That statement insisted that the breach occurred through a "third-party service provider" and that while hackers were able to "remotely access several Treasury user workstations and certain unclassified documents maintained by those users," there was no evidence to suggest that sensitive classified information was accessed or that the hackers maintained the capability to continue accessing the department's various offices and systems.

"Treasury takes very seriously all threats against our systems, and the data it holds," a spokesperson said at the time. "Over the last four years, Treasury has significantly bolstered its cyber defense, and we will continue to work with both private and public sector partners to protect our financial system from threat actors."

Hackers also gained access to sanctions office

The Washington Post previously reported that another highly sensitive office within the Treasury Department that deals with economic sanctions, the Office of Foreign Assets Control, was also breached as part of the broader China-linked hack, as was the Office of Financial Research.

Those two offices would undoubtedly hold information that the Chinese regime would like to know about current and possibly pending sanctions against Chinese entities and the anticipated impact those sanctions might have.

The Post noted that the Treasury Department breach was merely the latest in a series of Chinese hacks over the past year that targeted major telecoms companies, several U.S. officials and politicians, and other federal agencies.

Valid concerns raised by Treasury breach

According to Regtechtimes, and regardless of the Treasury's insistence that only unclassified information was accessed by the Chinese hackers, the breach of CFIUS and the sanctions office is concerning for multiple reasons.

The first and most obvious concern is that the breach exposed vulnerabilities in the U.S. government's cybersecurity efforts and revealed that federal departments and agencies are not as strongly secured from hacks as had been claimed.

Another major concern is that China, even if they only accessed unclassified information, could still piece together through careful intelligence analysis a revelatory view of how effective current and pending sanctions are and whether certain proposed investments in the U.S. will be approved or denied for national security reasons.