TikTok’s CEO has written to nine Republican senators to outline new efforts by the popular video app to protect US user data, amid renewed congressional scrutiny of access to that information by employees of its Chinese parent company, ByteDance. “We know we are among the most scrutinised platforms from a security standpoint, and we aim to remove any doubt about the security of US user data,” Shou Zi Chew wrote in the letter, which was dated Thursday and obtained by The New York Times. Steps taken by the company to address data security concerns included an initiative called “Project Texas,”...