North Korea and the U.S. flexed their military muscles Tuesday as Pyongyang marked the 85th anniversary of the founding of the Korean People's Army — without testing a nuclear weapon or conducting a major missile test.

Instead, amid soaring tensions on the Korean Peninsula, the nuclear-armed North carried out large-scale, live-fire drills in areas around the city of Wonsan on the country's east coast, South Korea's Defense Ministry said.

The Yonhap news agency said the drill, which involved 300-400 artillery pieces, was overseen by leader Kim Jong Un and was thought to be the "largest ever."