Washington — The U.S. Treasury department on Friday sanctioned Singaporean Yin Kechen and cybersecurity company Sichuan Juxinhe Network Technology Co., accusing both of being involved in a series of hacks against American telecom companies. The intrusions, known under the name “Salt Typhoon,” have allegedly exposed a huge swathe of Americans’ call logs to Chinese spies and rattled the U.S. intelligence community. In some cases, the hackers are alleged to have intercepted conversations,…