Written by David Pierson China’s top leader, Xi Jinping, rolled out the red carpet for President Luiz Inácio Lula da Silva of Brazil, lauding him as “an old friend of the Chinese people.” He sipped tea in a garden with President Emmanuel Macron of France, treating him to a performance of an ancient Chinese zither. And he talked on the phone with Crown Prince Mohammed bin Salman, Saudi Arabia’s de facto ruler, offering well wishes for the Muslim holy month of Ramadan. But even as Xi has offered a glad hand to those and other world leaders in recent weeks,...