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.

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.

Following criticism of the company’s use of Chinese workers to advise on operation of Department of Defense cloud systems, Microsoft has changed its policy.

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