For months behind the scenes in Beijing, Chinese and American officials have been locked in negotiations over one of the most consequential political meetings of this year. China's President Xi Jinping was set to host United States President Donald Trump at a highly choreographed reception in Beijing at the end of March.Iran war live updates: For all the latest news on the war in the Middle East, read our blog.At the top of the agenda was extending a fragile trade truce between the two superpowers, along with discussions around Taiwan, semiconductors, rare earths, and agriculture.But just days out from touchdown in…