North Korea Parade
A soldier stands guard in front of the portraits of North Korea founder Kim Il-sung, left, and the late leader Kim Jong-il during a military parade to celebrate the centenary of the birth of Kim Il-sung in Pyongyang April 15, 2012. Reuters/Bobby Yip

North Korea won’t be bullied by its enemies, third-generation dictator Kim Jong Un vowed in his first public address at a military parade as South Korea warned that his regime may conduct an atomic test.

Dressed in a dark Mao suit and standing on a podium high above Kim Il Sung Square in Pyongyang Saturday, the new leader said, “the days of enemies threatening and blackmailing us with nuclear weapons are forever over,” Bloomberg Businessweek reported. Goose-stepping soldiers, mobile rocket launchers and tanks rumbled through the streets below in a celebration broadcast on state television.

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

North Korea’s humiliation from a long-range rocket that disintegrated within minutes of liftoff Friday morning increases the chance of Kim ordering an atomic test to regain face, South Korean Deputy Defense Minister Lim Kwan Bin warned. The launch also ended a U.S. food-aid deal.

“Kim is very aware of how powerful the military is and knows his only strategy is to keep selling the ‘military-first’ policy,” said Koh Yu Hwan, a professor of North Korean studies at Seoul’s Dongguk University. “Stability is what the young Kim needs most and he needs the full support of the military.”

North Korea's legislature also rubber-stamped Kim Jong Un's leadership of the country and promoted a host of relatively younger military officials to the powerful National Defense Commission, state-run media reported Saturday, in a strong indication that will have an overarching role in policy, just as it did under his father, CBS reported.

Still, Premier Choe Yong Rim told legislators the nation's top priority is to build up the economy and improve the people's standard of living, according to the state-run Korean Central News Agency.

North Korea's Supreme People's Assembly convened Friday for a special one-day session to ratify appointments and promotions, discuss this year's budget and to make constitutional amendments to formalize Kim Jong Un's leadership of the country.

Saturday's parade was broadcast on North Korean state television and held to commemorate the centenary of the birth of Kim’s late grandfather, state founder Kim Il Sung. The younger Kim is thought to be less than 30 years old and assumed power after his father, Kim Jong Il, died of a heart attack on Dec. 17.

It also featured what appeared to be a new, larger ballistic missile, said Baek Seung Joo, who studies Pyongyang’s military at the Korea Institute for Defense Analyses in Seoul. South Korea’s Defense Ministry was unable to comment on the design or whether it was a real missile.

North Korea, officially at war with the South for 62 years, has 1.2 million people in its armed forces and has twice detonated an atomic device.

“The people’s army has conducted guerrilla warfare, regular combat and psychological warfare,” said Kim, who shuffled his feet as he read the speech from notes. “We have grown into a powerful military, equipped with our own means of defense and attack in any modern war.”

He didn’t mention the rocket launch or his regime’s atomic weapons program during the speech, which lasted 20 minutes. The South Korean Defense Ministry said last week’s rocket launch may have cost $800 million, equivalent to a year’s worth of food for the North’s 24 million people.

Outside analysts have raised worries about how Kim Jong Un, who has been seen but not publicly heard since taking over after his father's death, would govern a country that has a nuclear weapons program and has previously threatened Seoul and Washington with war.

At the celebration of Kim Il Sung, he appeared to clear his first hurdle.

The speech was a good first impression for his people and for the world, Hajime Izumi, a North Korea expert at Japan's Shizuoka University, told the AP. He demonstrated that he can speak in public fairly well, and at this stage that in itself -- more than what he actually said -- is important. I think we might be seeing him speak in public more often, and show a different style than his father.

Kim also stressed the importance of national unity, calling his country Kim Il Sung's Korea rather than North Korea.

That suggests to me that they want to let the country, and the world, know that this is a 'new' country, said Han S. Park, a University of Georgia professor.

Cha Myong Hui, a journalist with the government-run Minju Joson newspaper, said she was struck by how much he resembles his father and grandfather.

I can tell you every person in my country cried when they heard his voice, she said.