The launch happened hours after South Korean and U.S. troops kicked off their large annual combined drills, which the North views as an invasion rehearsal.

South Korea's suspension of some military drills after its fighter jets' accidental bombing of a civilian area may hinder its upcoming annual military training with the United States.

The South Korean military said the accident near the North Korean border occurred during training ahead of Freedom Shield, an annual U.S.-South Korea joint military exercise.