This isn't good. From the FT:

A full-blown trade row erupted on Sunday night between the US and China after Beijing accused Washington of "rampant protectionism" for imposing heavy duties on imported Chinese tyres and threatened action against imports of US poultry and vehicles.

Trade relations between two of the world's biggest economies deteriorated after Barack Obama, US president, signed an order late on Friday to impose a new duty of 35 per cent on Chinese tyre imports on top of an existing 4 per cent tariff.