A U.S. lawmaker on Thursday pressed the U.S. Defense Department for further details on what information the U.S. military shared with Chinese engineers as part of a cloud computing services contract with Microsoft.

Department of Homeland Security headquarters, several of its agencies and the Department of Health and Human Services have been hacked as part of a wider breach of Microsoft SharePoint.​

Chinese hackers breached the U.S. National Nuclear Security Administration through Microsoft SharePoint, with the Energy Department confirming no sensitive information was stolen.

A series of cyberattacks targeting Microsoft collaboration software, specifically SharePoint, have been linked to Chinese hackers and threat actors.

Microsoft has relied on engineers based in China for years to help maintain some of the U.S. Department of Defense’s

Defense Secretary Pete Hegseth says the DOD is "looking into" a Microsoft cloud program that used Chinese engineers after an investigative report raised concerns about CCP access.

Microsoft has pointed the finger at three Chinese nation-state actors for exploiting the SharePoint vulnerabilities. Here's what we know about the security flaws and how to guard against future attacks.