قمة ترامب وشي: التجارة وتايوان وإيران على الطاولة في اجتماع بكين عالي المخاطر

US President Donald Trump's highly anticipated visit to Beijing on Wednesday comes at a restless moment for a world worried about war and trade disputes. Trump has said he will have a "long talk" about Iran with Chinese leader Xi Jinping and will also discuss US arms sales to Taiwan. Here's what to know about the summit.