North Korean television has aired a documentary to honor what is reported to be the birthday of its new leader, Kim Jong-Un.

The footage shows Kim Jong-Un in his new role as supreme military commander – inspecting troops, saluting and sitting in a tank.

The documentary also confirms that Kim Jong-Un was being groomed for the role from 2009, showing footage of him from that time watching a rocket launch with his father, Kim Jong-Il.

Kim Jong-un’s age is not known but he is believed to be in his late 20s.

The death of Kim Jong-Il on 17 December left the threat of a dangerous vacuum in a society raised to venerate one supreme leader.

Less than a month on, North Korea’s unique media machine is already working to fill it.

The footage shows Kim Jong-Un in his new role as supreme military commander - inspecting troops, saluting and sitting in a tank

The documentary shows Kim Jong-Un manoeuvring a tank, watching jet fighter and firing exercises and posing for photographs with soldiers.

The film also shows Kim Jong-Un with his father shaking hands with officials at a satellite control centre after scientists launched a rocket in April 2009.

“I had decided to wage a real war if the enemies shot down the rocket,” Kim Jong-Un is quoted as saying.

The documentary also shows him visiting factories, talking to officials and inspecting their work – all the things his father used to do.

Websites linked to the North Korean government have already begun describing the new leader as having the wisdom of great men, extraordinary competence and military brilliance.

Kim Jong-Un was named “supreme leader of the party, state and army” following the death of Kim Jon-Il.

The young leader has already pledged to continue with Kim Jong-Il’s “military first” policies.