New footage on North Korean state TV shows young leader Kim Jong-un maneuvering a tank and observing firing exercises.

State TV aired the footage Sunday on what is believed to be Kim Jong-un ’s birthday. His birth date has never been revealed, however, and there has been no mention of his birthday in state media.

Mr. Kim was named “supreme leader” of North Korea’s people, ruling party and military last month after the death of his father, Kim Jong il. The process to consolidate Kim Jong-un’s power has been gaining speed.

The footage Sunday showed Mr. Kim reviewing military exercises, including planes tearing through the sky and soldiers dropping down in parachutes. Mr. Kim has pledged to uphold his father’s “military first” policy.

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