Xi Jinping, China's president, during a bilateral meeting Dina Boluarte, Peru's president, not pictured, at the Government Palace in Lima, Peru, on Thursday. (Photo: Bloomberg)LIMA — As United States President-elect Donald Trump threatens to impose tariffs on the entire world, Xi Jinping is once again wasting no time in positioning himself as the premier defender of the international trading system. China's leader warned on Friday that the global economy was fracturing as protectionism spreads, leading to "severe challenges." For Xi, it is a role he played when Trump first rose to power in 2017. "It wasn't easy," Trudeau said of the first round of trade discussions with Trump.