Chinese state-sponsored hackers broke into the US Treasury Department earlier this month and stole documents from its workstations, according to a letter to lawmakers that was provided to Reuters on Monday. The hackers compromised a third-party cybersecurity service provider and were able to access unclassified documents, the letter said, calling it a "major incident." According to the letter, hackers "gained access to a key used by the vendor to secure a cloud-based service used to remotely provide technical support for Treasury Departmental Offices (DO) end users. With access to the stolen key, the threat actor was able override the service’s...