SEOUL, South Korea (AP) — North Korea said Friday it test-launched new anti-aircraft missiles, as its military threatened unspecified grave steps against the U.S. and South Korea over their joint military drills that it views as an invasion rehearsal. The official Korean Central News Agency said that leader Kim Jong Un oversaw the tests Thursday and called the missiles involved “another major defense weapons system” for North Korea. The missile launches, North Korea’s sixth weapons testing activity this year, occurred on the same day that the U.S. and South Korean militaries concluded their annual Freedom Shield command post exercise.