WASHINGTON, April 14 (Reuters) - Washington on Friday imposed sanctions on two entities based in China, accusing them supplying precursor chemicals to drug cartels in Mexico for the production of illicit fentanyl intended for the United States, the U.S. Treasury Department said in a statement. The Treasury said it also designated five people based in China and Guatemala in the action targeting fentanyl production. "Illicit fentanyl is responsible for the deaths of tens of thousands of Americans each year," the Treasury's under secretary for terrorism and financial intelligence, Brian Nelson, said in the statement. "Treasury, as part of the whole-of-government...