(CNN) — North Korea’s military staged a “large-scale artillery drill” in the country’s east Tuesday to mark the founding of the country’s army.

A statement from the South Korean military said the live-fire exercises were underway in the Wonsan region on Tuesday afternoon, but gave no details on what kinds of weapons and military units took part in the drill.

“Our military is closely monitoring the North Korean military’s movements and remains firmly prepared,” the statement from the South Korean Joint Chiefs of Staff says.

North Korea’s drills coincided with military exercises held by US and South Korean navies in the Yellow Sea, off the western coast of the Korean Peninsula.