North Korean space officials have moved all three stages of a long-range rocket into position for a controversial launch, vowing Sunday to push ahead with their plan in defiance of international warnings against violating a ban on missile activity.

Foreign news agencies allowed a firsthand look at preparations under way at the coastal Sohae Satellite Station in northwestern North Korea.

North Korea announced plans last month to launch an observation satellite using a three-stage rocket during mid-April celebrations of the 100th anniversary of the birth of North Korean founder Kim Il Sung. The U.S., Japan, Britain and other nations have urged North Korea to cancel the launch, warning that firing the long-range rocket would violate U.N. resolutions and North Korea's promise to refrain from engaging in nuclear and missile activity.

North Korea maintains that the launch is a scientific achievement intended to improve the nation's faltering economy by providing detailed surveys of the countryside.

"Our country has the right and also the obligation to develop satellites and launching vehicles," Jang Myong Jin, general manager of the launch facility, said during a tour, citing the U.N. space treaty. "No matter what others say, we are doing this for peaceful purposes."

Experts say the Unha-3 rocket slated for liftoff between April 12 and 16 could also test long-range missile technology that might be used to strike the U.S. and other targets.

North Korea has tested two atomic devices, but is not believed to have mastered the technology needed to mount a warhead on a long-range missile.

On Sunday, reporters were taken by train past desolate fields and sleepy farming hamlets to North Korea's new launch pad in Tongchang-ri in North Phyongan province, about 50 kilometers (35 miles) south of the border town of Sinuiju along North Korea's west coast.

All three stages of the 91-ton rocket, emblazoned with the North Korean flag and "Unha-3," were visibly in position at the towering launch pad, and fueling will begin soon, Jang said. He said preparations were well on track for liftoff and that international space, aviation and maritime authorities had been advised of the plan, but did not provide exact details on the timing of the fueling or the mounting of the satellite.

Engineers gave reporters a peek at the 100-kilogram (220-pound) Kwangmyongsong-3 satellite due to be mounted on the rocket, as well as a tour of the command center.

About two weeks before North Korea unveiled its rocket plan, Washington announced an agreement with the North to provide it with much-needed food aid in exchange for a freeze on nuclear activity, including a moratorium on long-range missile tests. Plans to send food aid, as well as a recently revived project to conduct joint searches for the remains of U.S. military personnel killed during the Korean War, have now been suspended.

Jang denied the launch was a cover for a missile test, saying the relatively diminutive rocket and fixed Sohae station would be "useless" for sending a mobile intercontinental ballistic missile.

"During the recent senior-level North Korea-U.S. talks, our side made clear there's only a moratorium on long-range missile launches, not on satellite launches," he said. "The U.S. was well aware of this."

Japan and South Korea, meanwhile, said they are prepared to shoot down any parts of the rocket that threaten to fall in their territory - a move North Korea's Foreign Ministry warned would be considered a declaration of war.

The launch is scheduled to take place three years after North Korea's last announced attempt to send a satellite into space, a liftoff condemned by the U.N. Security Council. North Korea walked away from nuclear disarmament negotiations in protest, and conducted an atomic test weeks later that drew tightened U.N. sanctions.

It is meant to show that North Korea has become a powerful, prosperous nation, celebrate the centenary of founder Kim Il Sung's birth, and usher in a new era under his grandson, Kim Jong Un, said Koh Yu-hwan, a professor of North Korean studies at Seoul's Dongguk University.

"North Korea needs to show some tangible achievements to its people to solidify Kim Jong Un's leadership," he said. "North Korea intends to provide its people with a sense of pride."

Kim Jong Un took power following the December death of his father, longtime leader Kim Jong Il, and is expected to assume more top posts during high-profile political and parliamentary meetings later this week - a step analysts say will formally complete the country's second hereditary power transfer.

The satellite is designed to send back images and information that will be used for weather forecasts as well as surveys of North Korea's natural resources, Jang said. He said a western launch was chosen to avoid showering neighboring nations with debris.

He said two previous satellites also named Kwangmyongsong, or Bright Shining Star, were experimental, but the third will be operational.

However, Brian Weeden, a technical adviser at Secure World Foundation who is a former Air Force officer at the U.S. Space Command, questioned whether North Korea truly has the technology to successfully send a satellite into orbit.

"The end goal is to test and develop their ballistic missile program and show their people and the world that they are strong," Weeden said from Washington.