The U.S. imposed export restrictions on Taiwan's Semiconductor Manufacturing International Corp. (SMIC) adding to tensions between with China over the critical industry. U.S. firms must now apply for a license to export certain products to China’s largest chipmaker, the Commerce Department said in a letter dated September 25, reviewed by Bloomberg News. SMIC and its subsidiaries present “an unacceptable risk of diversion to a military end use,” the department’s Bureau of Industry and Security wrote. SMIC has not been put on the so-called U.S. entity list.