He could soon preside over a full-scale proxy war, or else do the Nixon-to-China routine with Rouhani. There is simply no way of knowing.
Trump is now on his fourth National Security Adviser. By the time the election comes, expect him to be on his fifth or sixth.
As with the NHS, policing, immigration and stop & search, so with trade. The Prime Minister will want a quick win – or at least progress towards one.