US

S. Korea, US start drills despite N. Korea's nuclear threat

  • South Korean President Park Geun-hye. second from left, presides over a session of the National Security Council at the presidential house in Seoul, South Korea, Monday, Aug. 22, 2016. South Korea and the United States began annual military drills Monday despite North Korea's threat of nuclear strikes in response to the exercises that it calls an invasion rehearsal. (Baek Seung-ryul/Yonhap via AP)

    South Korean President Park Geun-hye. second from left, presides over a session of the National Security Council at the presidential house in Seoul, South Korea, Monday, Aug. 22, 2016. South Korea and the United States began annual military drills Monday despite North Korea's threat of nuclear strikes in response to the exercises that it calls an invasion rehearsal. (Baek Seung-ryul/Yonhap via AP)  (The Associated Press)

  • South Korean President Park Geun-hye speaks during a session of the National Security Council at the presidential house in Seoul, South Korea, Monday, Aug. 22, 2016. South Korea and the United States began annual military drills Monday despite North Korea's threat of nuclear strikes in response to the exercises that it calls an invasion rehearsal. (Baek Seung-ryul/Yonhap via AP)

    South Korean President Park Geun-hye speaks during a session of the National Security Council at the presidential house in Seoul, South Korea, Monday, Aug. 22, 2016. South Korea and the United States began annual military drills Monday despite North Korea's threat of nuclear strikes in response to the exercises that it calls an invasion rehearsal. (Baek Seung-ryul/Yonhap via AP)  (The Associated Press)

  • South Korean protesters stage a rally demanding to stop the joint military exercises, Ulchi Freedom Guardian, or UFG, between the U.S. and South Korea near U.S. Embassy in Seoul, South Korea, Monday, Aug. 22, 2016. South Korea and the United States began annual military drills Monday despite North Korea's threat of nuclear strikes in response to the exercises that it calls an invasion rehearsal. Signs held by the protesters read: "Stop Ulchi Freedom Guardian exercise and war exercise." (AP Photo/Ahn Young-joon)

    South Korean protesters stage a rally demanding to stop the joint military exercises, Ulchi Freedom Guardian, or UFG, between the U.S. and South Korea near U.S. Embassy in Seoul, South Korea, Monday, Aug. 22, 2016. South Korea and the United States began annual military drills Monday despite North Korea's threat of nuclear strikes in response to the exercises that it calls an invasion rehearsal. Signs held by the protesters read: "Stop Ulchi Freedom Guardian exercise and war exercise." (AP Photo/Ahn Young-joon)  (The Associated Press)

South Korea and the United States have begun annual military drills despite North Korea's threat to launch nuclear strikes in response to the exercises that it calls an invasion rehearsal.

Such fiery rhetoric by Pyongyang is not unusual. But the latest warning comes at a time of more tension following the defection of a senior North Korean diplomat and a U.S. plan to place a high-tech missile system in South Korea.

The North's military said in a statement Monday that it will turn Seoul and Washington into "a heap of ashes through a Korean-style pre-emptive nuclear strike" if they show any signs of aggression toward the North's territory.

The Ulchi Freedom Guardian drills that began Monday for a 12-day run is largely computer-simulated war games.