All three ballistic missiles launched by North Korea on Monday were medium-range Rodong-class and flew about 1,000 km (600 miles), South Korea's military said.

At least one of the missiles fell into Japan's Air Defence Identification Zone, a South Korean military official said by telephone.

The launches were likely a show of force by the North's military timed to coincide with the Group of 20 leaders' summit taking place in China, the South's Office of the Joint Chiefs of Staff said separate in a statement.