Stock markets responded on Wednesday to Trump's statements that negotiations with Iran are taking too long and the U.S. is planning more strikes against the country. 

The Dow Jones Industrial Average fell by 711 points, or 1.4%, and the S&P was down 1.2%. The Nasdaq Composite traded down 1.6%, CNBC reported. 

West Texas Intermediate oil prices, the American benchmark, had fallen at the end of May from highs over $100 per barrel, to the mid $80s at the start of June. They were down on Tuesday, as Trump said on Tuesday that a peace deal was close. 

When it turned out an Apache helicopter had been taken down by Iranian forces and hostilities resumed, oil prices reversed on Wednesday. By afternoon, they were at $91.60 per barrel. 

Jed Ellerbroek, portfolio manager at Argent Capital Management, told CNBC that, if the U.S. doesn't come to a peace deal with Iran that opens up the Strait of Hormuz, oil prices are "going to have to come up a lot." He said that in this investing environment, "it's impossible to be comfortable."