China’s top diplomat warned the US not to cross a “red line,” in an endeavor to steer a delicate bilateral relationship toward areas of cooperation as President Biden signals continuity with previous administrations on hot-button issues including Hong Kong and Xinjiang.Yang Jiechi on Tuesday Beijing time emphasized the potential for a healthy US China relationship on public health, trade and climate, echoing recent language from leader Xi Jinping. But he left limited room for negotiation on issues such as human rights, the coronavirus response and what he called US interference in Taiwan, Hong Kong, Tibet and Xinjiang.Secretary of State Antony Blinken had in an interview that aired hours earlier on MSNBC criticized China for having broken its promises on Hong Kong’s autonomy and handling of the coronavirus outbreak with a lack of transparency. Mr. Blinken-whose message slightly diverged from that of his predecessor, Mike Pompeo-described China as a “significant challenge” to the US but said strong alliances are an advantage for Washington confronting China.