https://www.theregister.co.uk/2019/05/15/president_trump_huawei_emergency_ban/

President Donald J. Trump today declared yet another national emergency in the US – this one over the threat of unidentified foreign adversaries exploiting vulnerabilities in IT and telecom systems and services.

Short on specifics, the freshly signed executive order authorizes the Secretary of Commerce "to prohibit transactions posing an unacceptable risk to the national security of the United States or the security and safety of United States persons," the White House said in a statement.