The United States is the latest country to advise its athletes against taking personal cellphones to the Beijing Winter Olympics, set to start Feb. 4. The U.K., Canada, and the Netherlands have already taken the unusual step in suggesting athletes use burner or disposable phones rather than putting their personal devices at risk of being monitored by China’s notorious censors. The bulletin sent to athletes in September and again in December warned: “every device, communication, transaction and online activity may be monitored. Your device(s) may also be compromised with malicious software, which could negatively impact future use.”