Identifying who will go from anger to violence is like "trying to find which piece of hay is going to become a needle," one expert said.

Watch live as the stock market reacts after President Trump posted on social media that he would be considering a 50% tariff on the European Union as trade talks have stalled.

President Donald Trump has threatened Apple with a 25% tariff if it does not start producing iPhones in the U.S., his latest salvo directly targeting a U.S. company over how it conducts its business.