North Korea has warned of "more powerful follow-up measures" in response after the United States intensified joint military exercises with South Korea.
The secretive state has claimed that the military activities by its neighbours in the south and the Americans are practice ahead of a potential invasion.
Aerial drills involving more than 200 warplanes, including their advanced F-35 fighter jets, have been carried out by the US and South Korea as they step up their defence posture in the face of North Korea's increased weapons testing and growing nuclear threat.
