BOSTON (AP) — Microsoft says state-backed Russian hackers broke into its corporate email system and accessed accounts of members of the company’s leadership team, as well as those of cybersecurity and legal employees.

In a blog post, Microsoft said the intrusion began in late November and was discovered on Jan. 12. It said the same highly skilled Russian hacking team behind the SolarWinds breach was responsible.

The company says a very small percentage of Microsoft corporate accounts were accessed and some emails and documents were stolen.

A Microsoft spokesperson had no immediate comment on which or how many members of the company’s senior leadership had their email accounts breached.