PYONGYANG, North Korea -- North Korea vowed today to stage an all-out drive for prosperity as it unites behind new leader Kim Jong Un, ushering in 2012 with promises to resolve food shortages, bolster its military and defend Kim Jong Il's young son "unto death."

The pledge in North Korea's annual New Year's message, released by the official Korean Central News Agency, comes as the country enters a new era, with Kim Jong Un installed as Supreme Commander of the 1.2 million-strong military and ruling party leader following his father's Dec. 17 death.

This year is a crucial one in North Korea's history as it tries to build a "great and prosperous nation" befitting the April 2012 centenary of the birth of national founder Kim Il Sung, the new leader's grandfather.

"Glorify this year 2012 as a year of proud victory, a year when an era of prosperity is unfolding," the North said. "The whole Party, the entire army and all the people should possess a firm conviction that they will become human bulwarks and human shields in defending Kim Jong Un unto death."

North Korea said it would boost its military, and boasted that it was "at the epochal point of opening the gates of a thriving country," with parts of Pyongyang "turned into socialist fairylands."

Still, the message also acknowledged the country's food crisis, saying "the food problem is a burning issue." Pyongyang had been in talks with the United States on food aid before Kim Jong Il's death.

The United Nations has said a quarter of North Korea's 24 million people need outside food aid and that malnutrition is surging, especially among children.

The North's message did not give specifics for improving food supplies, other than saying the party's policy of agricultural revolution should increase yields.

North Korea's traditional New Year's Day message is always closely watched for clues to the government's plans.

North Korea in recent days has cemented Kim Jong Un's position as leader, and on Saturday officially named him Supreme Commander over the military.

"The entire army should place absolute trust in and follow Kim Jong Un," the New Year's message said.

The North linked Kim Jong Un to the "songun," or military-first, policy of Kim Jong Il, and called him "the eternal center" of the country's unity. In fact, the editorial said, "The dear respected Kim Jong Un is precisely the great Kim Jong Il."

The message spoke of a desire for reunification with South Korea, but did not give specifics.