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.

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.

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

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

A security patch Microsoft (MSFT.O), opens new tab released this month failed to fully fix a critical flaw in the U.S. tech giant's SharePoint server software, opening the door to a sweeping global cyber espionage effort,

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

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.

The move comes after a ProPublica report highlighted a Microsoft program that allows foreign engineers to indirectly interact with U.S. military systems through American “escort” intermediaries.

Technicians from China took care of the Department of Defense's cloud on behalf of Microsoft. After this came to light, the provider had to rebuild.