Cyberattackers linked to a Chinese spy agency conducted a major ransomware attack against an American company, adding a new layer of complexity to a threat usually attributed to Russia, according to President Joe Biden’s administration.

“This was surprising to us,” a senior administration official acknowledged in a media briefing Sunday on how China’s Ministry of State Security has emerged as a major cybersecurity threat. “And, in fact, one of the reasons that we’ve put so much work into this attribution is because it really gave us new insights on the MSS’s work and on the kind of aggressive behavior that we’re seeing coming out of China.”