United States President Donald Trump signed an executive order on Wednesday to stop US companies from using telecommunications equipment made by technology firms that pose a national security risk. The order paves the way for a ban on doing business with China's Huawei, though it did not name specific countries or companies. Such action was under consideration for more than a year, but was repeatedly delayed. Under the International Emergency Economic Powers Act, the president has the authority to regulate business decisions in response to a clear national threat, and the "national emergency" declaration directs the US Department of Commerce...