David Guttenfelder / AP

North Koreans gather to put flowers on a stage in front of a portrait of Kim Jong Il as they pay their respects on the first day of the Lunar New Year holiday at Kim Il Sung Square in Pyongyang on Monday.

PYONGYANG, North Korea - Bundled up against the freezing cold, soldiers and children lined up Monday at Pyongyang's main plaza to pay their respects again to late leader Kim Jong Il.

It was North Korea's unique way of marking the lunar New Year which was celebrated in China and elsewhere in the region with fireworks.

A massive portrait of Kim that had been taken down after a mourning period following his Dec. 17 death was back up at Kim Il Sung Square.

People scurried across the vast plaza to get in line to bow and lay single red flowers, the late leader's namesake "kimjongilia" begonias, made of fabric. The song "It's snowing" blared from the loudspeakers, a reminder of Kim's solemn funeral procession through the capital city's snowy streets late last month.

For several weeks after the funeral, Pyongyang was barren and somber. But almost overnight the city has filled with color again. North Korea's red, white and blue national flag fluttered from signposts. Banners celebrating "Juche 101" — the current year, according to the North Korean calendar, which begins with the 1912 birth of national founder Kim Il Sung — and posters marking the holiday were pinned to buildings and walls.

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At the plaza in front of the Pyongyang Grand Theater, hundreds of children scampered and shouted as they played traditional Korean games in frigid temperatures. Signs in front of the theater spelled out "We are happy" in big, bold letters.

Pyongyang residents said they were encouraged to celebrate the traditional holiday as they usually do, despite the death of Kim Jong Il, only the second leader North Koreans have known since the nation was founded in 1948. State television aired a segment late Sunday on making rice cake soup, a traditional New Year's meal in both Koreas.

The holiday comes as new leader Kim Jong Un makes a round of visits to military units.

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Outside observers have raised questions about whether Kim Jong Un — who's believed to be aged in his late 20s — is ready to rule a country of 24 million with a nuclear program as well as chronic food shortages.

But the North has dismissed such worries, and state media have put out a stream of reports and images meant to show that Kim has strong military and governing experience. Late last week, for example, North Korea credited Kim Jong Un with spearheading past nuclear testing and said he was "fully equipped" with the qualities of an extraordinary general.

Kim Jong Un, anointed his father's successor at least three years ago, was declared "supreme leader" of the North Korean people, party and military after his father's death. He has pledged to uphold his father's "military first" policy.

The new era of leadership comes as North Korea prepares to celebrate the 100th anniversary in April of the birth of his grandfather, late President Kim Il Sung.

The Associated Press and msnbc.com staff contributed to this report.