The U.S. Commerce Department is probing whether a South Korean maker of parts for machines that produce semiconductors has been selling to Chinese companies that are subject to U.S. sanctions, said two people with knowledge of the investigation. The review signals a new effort by the U.S. government to root out how companies such as Huawei are getting access to crucial chip-making technology, despite escalating U.S. export controls.The officials are investigating whether Ronda Korea has been sel...