North Korean leader Kim Jong Un (Photo: Yonhap/VNA)

The "contest" involved war planes, multiple-rocket launchers and self-propelled guns that attacked the targets. 
The launches came amid the ongoing joint U.S.-South Korea Ulchi Freedom Guardian war games, a largely computer-simulated exercise that runs for two weeks in the South.

North Korea launched three short-range ballistic missiles early Saturday, with two flying roughly 250 km and the other exploding almost immediately. The US announced that those missile launches did not pose a threat to Guam, the island and unincorporated territory of the United States in the North Pacific Ocean.

South Korea said the three launches occurred near in eastern Gangwon province.