The U.S. Treasury Department on Friday imposed sanctions on alleged hacker Yin Kecheng and cybersecurity company Sichuan Juxinhe Network Technology Co., accusing both of being involved in a series of hacks against American telecom companies.

US Treasury Secretary Janet Yellen’s computer was infiltrated and unclassified files were accessed as part of a broader breach of the agency by Chinese state-sponsored hackers, according to two people familiar with the matter.

The U.S. Treasury department on Friday issued cyber-related sanctions related to the Salt Typhoon hack on Singaporean Yin Kechen and cybersecurity company Sichuan Juxinhe Network Technology Co., according to a statement.