U.S. Special Representative for North Korea, Sung Kim, left, shakes hands with South Korea's Special Representative for Korean Peninsula Peace and Security Affairs Kim Gunn, prior to a meeting at the Foreign Ministry Thursday, April 6, 2023 in Seoul, South Korea. (Song Kyung-Seok/Pool Photo via AP) SEOUL – North Korea on Thursday threatened unspecified “offensive action” over the expansion of U.S. military exercises with rival South Korea as President Joe Biden’s special representative for North Korea flew to Seoul for talks with allies over the North’s growing nuclear threat. The North Korean comments came a day after the United States...