South Korea test fires one of its missiles, left, after the U.S. Army fired one of its missiles, right, during a combined military exercise between the two countries at an undisclosed location in South Korea, July 29, 2017. This exercise was after held North Korea conducted its second flight test this year of an intercontinental ballistic missile, with North Korean leader Kim Jong claiming that the latest one demonstrates his country can hit the U.S. mainland. South Korea Defense Ministry AP