Trade deals and tariffs

[UndersAndOvers]

Not actually Brexit but it if I put it in chat it may be overlooked as a Brexit thread.
We have been told, that if we go onto WTO terms, if we reduce tariffs for one country we have to do it for all.
So, how can the US suddenly increase tariffs just for Chinese goods?

I'm not 100% certain but i imagine it's because the USA don't trade solely on WTO terms like we would be, in fact we'd be the only country on the planet who would trade this way.

The US have many individual trade agreements in place which allow them to dictate different terms to different countries.

Answering my own question here - Is it that the US and China have a deal now and this tit for tat tariff increases is just a renegotiation of terms - though somewhat aggressive and public?

It's not a renegotiation, it's unilateral. It's all allowed for within the WTO framework though. They inform the WTO of any particular measures they want to take regarding a particular country or commodity and it's up to other members whether they dispute their right to take the measure or apply their own retaliatory measures.

As an example, here's the EU decision to increase the import duty on certain items from the USA eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32018R0886&qid=1549361949906&from=EN

So in a No Deal Brexit world, UK could say we will have zero tariff on EU goods. But it'd be up to other countries in WTO to object to it?