Let's see... the Fed decided to unload their balance sheet, in the Fall of 2017, that expanded from QE years, interest rate (real) finally looks like it's getting out of negative territory, political uncertainty(including China trade wars), high PE ratio than historical average in the markets, what else did they usually look at for needing a correction?
The unlimited money printing ended (or paused? who know what they will do) so there isn't enough money to push the market higher is how I see it. Trump probably just aggrevated it and made the future look uncertain, rather than full on cause it.
https://www.investopedia.com/articles/forex/072915/how-petrodollars-affect-us-dollar.asp