Frank Gardner: What is China's role in the Iran war?

China is the number one importer of Iranian oil, making it vulnerable to any constriction of exports in the Gulf. A US blockade of Iran's ports has been condemned by Beijing as "irresponsible and dangerous". China has reportedly sought to mediate the conflict by steering Iran towards talks with the US in Pakistan. The blockade poses significant risks to both the US and China, including political, economic, and military consequences.