North Korea’s new leader addressed his nation and the world for the first time Sunday, vowing to place top priority on his impoverished country’s military, which promptly unveiled a new long-range missile.

The speech was the culmination of two weeks of celebrations marking the centenary of the birth of his grandfather, national founder Kim Il Sung — festivities that were marred by a failed launch Friday of a rocket that generated international condemnation and cost North Korea a food aid-for-nuclear-freeze deal with Washington.

Kim Jong Un’s speech took North Koreans gathered at Kim Il Sung Square and around televisions across the country by surprise. His father, late leader Kim Jong Il, addressed the public only once in his lifetime.

Appearing calm and measured as he read the 20-minute speech, Kim Jong Un covered a wide range of topics, from foreign policy to the economy. His speech, and a military parade that followed, capped the carefully choreographed festivities commemorating Kim Il Sung’s birthday, which included a massive fireworks display.

It was the best look yet the outside world has had of the young Kim, who is believed to be in his late 20s.

Punctuating Kim’s message that the North will continue to pour funds into its military, the parade culminated with the unveiling of a new long-range missile, though it’s not clear how powerful or significant the addition to the North Korean arsenal is. Some analysts suggested it might have been a dummy designed to dupe outside observers.

Although the rocket launch Friday was a huge, costly embarrassment for the new leadership, Kim’s address was seen by analysts as an expression of confidence by the young leader and meant to show that he is firmly in control.

“Superiority in military technology is no longer monopolized by imperialists, and the era of enemies using atomic bombs to threaten and blackmail us is forever over,’’ Kim said.