With many Koreans still aggravated by U.S. President Donald Trump's controversial comment that "Korea used to be a part of China," his closest business partner, Vice President Mike Pence, has jangled  their nerves again. During a Tuesday meeting with  Japanese Prime Minister Shinzo Abe, Pence called the body of water  between the Korean Peninsula and Japan the "Sea of Japan." The name has been a long-standing point of conflict between Seoul and Tokyo, which the former has promoted as the "East Sea."