The South Korean military says North Korea fired multiple short-range ballistic missiles eastward on Thursday morning. They reportedly flew some 360 kilometers and fell into the Sea of Japan.

South Korea's Joint Chiefs of Staff announced that the missiles were fired at around 7:10 a.m. from near Pyongyang.

South Korea's Yonhap News Agency says if the missiles were fired southward, they would have had key South Korean military facilities within range.

South Korean experts suggest the missiles were what the North calls 600-millimeter "super-large rockets."

This is the first ballistic missile launch by North Korea since July 1.

North Korea launched "super-large rockets" in late May, with the country's leader Kim Jong Un watching.

Pyongyang stressed it aims to show it will not hesitate to carry out preemptive attacks.

The Joint Chiefs of Staff said at a news conference on Thursday that the missile launch could be a protest against last month's joint US-South Korea military exercise and last week's large-scale landing drill that was shown to the media.

The South Korean and US militaries are analyzing details of the launch and bracing for possible further provocations.