Microsoft has warned that Chinese state-sponsored hackers have breached its SharePoint software used by the US agency responsible for maintaining and modernizing the nation’s stockpile of nuclear weapons, according to a report.

Hackers sponsored by the Chinese state have breached a number of U.S. government institutions, including the agency responsible for overseeing the security of America’s nuclear arsenal, Microsoft warned.

The Chinese government has warned against using cyber security issues to defame the country, following the hacker attacks on Microsoft software. Foreign Ministry spokesman Guo Jiakun said in Beijing on Wednesday that he was not aware of the exact circumstances of the attacks.

In ongoing hacks, Microsoft says it has identified two Chinese hacking groups taking advantage of a key software flaw.

A critical flaw in Microsoft’s SharePoint software allowed China-linked hackers to breach dozens of systems worldwide, including US federal agencies and the nuclear weapons agency. Though no classified data has been confirmed stolen,

Chinese state-sponsored hackers have exploited vulnerabilities in Microsoft software to breach sensitive systems around the world, including those of the

After a ProPublica investigation raised security concerns, Microsoft will cease using China-based engineers for work on sensitive Pentagon cloud computing systems.

Microsoft confirms Chinese hackers exploited a SharePoint flaw; Patches now available. Cloud-based Microsoft 365 not affected.

The change follows a ProPublica report that outlined how Microsoft’s use of Chinese engineers left U.S. defense clients vulnerable to cybersecurity risks.