As the number one importer of Iranian oil, China has a major problem with any constriction of exports in the Gulf - including the US blockade of Iran's ports, which began on Monday.
Beijing has condemned the US blockade, calling it "irresponsible and dangerous".
It has also reportedly sought to play peacemaker in the conflict, steering its ally Iran towards talks with the US in Pakistan last weekend.
But the blockade creates a serious political, economic, and possibly military risk that both the US and China will want to avoid.
The BBC's security correspondent Frank Gardner explains why China's role in the conflict is too big to be ignored.
