Trumpers' plan for "Maximum pressure" on Iran, including secondary sanctions on Chinese oil purchasers.
Maximum pressure only worked last time because it reversed the benefits of the nuclear deal. That's not repeatable.
I hope that China isn't going to obey American orders and impose sanctions on Iran, only for Trump to then focus on his trade war against China. If China is going to be sanctioned anyway, you might as well buy Iranian oil and supply them with more anti ship missiles and air defence