Microsoft President Brad Smith will testify before a House of Representatives panel on homeland security on Thursday, fielding questions about the company’s security practices after Russian and Chinese hackers breached its systems over the past year.

China-linked hackers stole 60,000 U.S. State Department emails last year by breaking into the tech giant’s systems, while a Russian group spied on Microsoft’s senior staff emails earlier this year, according to the company’s disclosures.

In a scathing report in April, the Cyber Safety Review Board - formed by U.S. Secretary of Homeland Security Alejandro Mayorkas - slammed Microsoft for its lack of transparency over the Chinese hack, which the board said had been preventable.