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.

Researchers say Chinese actors, along with other criminal hackers, exploited a security flaw in SharePoint software widely used by governments and businesses.

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.