Afghanistan, Aug. 10 -- The United States has activated a sweeping new tariff regime, raising duties on imports from dozens of countries, with rates ranging from 10 percent to as high as 50 percent. The measures, signed by President Donald Trump on July 31, came into force at 12:01 a.m. Eastern Time on August 7, with U.S. Customs instructed to begin immediate collection. Goods already shipped before the deadline will be allowed to clear under previous rules if they arrive by October 5, according to the White House announcement.

Under the new policy, countries not listed for special treatment default to a 10 percent "reciprocal" tariff. The European Union negotiated a framework capping most of its goods at a total 15 percent duty if current...