SEOUL, South Korea—South Korea’s supermarket chains resumed selling U.S. beef Thursday, nearly five months after the government lifted an import ban imposed over fears of mad cow disease. South Korea banned American beef in 2003 after a case of mad cow disease was discovered in the U.S. The government lifted that ban in June —a move that sparked weeks of violent protests by South Koreans concerned about the health risks of eating U.S. meat. U.S. beef has been available in small butcher shops and some restaurants, but major supermarkets and larger restaurants have been shying away from offering U.S. beef out of concerns of possible public backlash. On Thursday, however, large discount department stores including E-mart, Home Plus and Lotte Mart began selling U.S. beef at 250 local branches, saying customers are demanding cheaper meat, according to the Korea Chainstores Association.