GANGWON-DO, SOUTH KOREA - SEPTEMBER 18:  In this handout image provided by South Korean Defense Ministry, U.S. Air Force B-1B Lancer bombers flying with F-35B fighter jets and South Korean Air Force F-15K fighter jets during a training at the Pilsung Firing Range on September 18, 2017 in Gangwon-do, South Korea. U.S. F-35B stealth jets and B-1B bombers flew near the Military Demarcation Line (MDL) for the first time since recent tension between U.S. and North Korea started raising.  (Photo by South Korean Defense Ministry via Getty Images)