Space officials told reporters at a news conference in Pyongyang that the launch of the three-stage rocket is on target to take place between Thursday and Monday as part of centennial birthday commemorations for late President Kim Il Sung, the country's founder.
"All the assembly and preparations of the satellite launch are done," including fueling of the rocket, he said.
The United States, Britain, Japan and others have urged North Korea to cancel the launch, saying it would be considered a violation of U.N. resolutions prohibiting the country from nuclear and ballistic missile activity.
Experts say the Unha-3 carrier is the same type of rocket that would be used to launch a long-range missile aimed at 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 nuclear warhead on a long-range missile.
Ryu acknowledged similarities between the rockets used for launching a satellite and a ballistic missile. However, he noted that solid fuel is used to launch ballistic missiles, while the Kwangmyongsong-3 satellite will be sent using liquid fuel.
Also, in order to be a success, a ballistic missile would require a large payload, he said.
"Our satellite weighs 100 kilograms. For a weapon, a 100-kilogram payload wouldn't be very effective," he said, dismissing assertions that the launch is a cover for developing missile technology as "nonsense."
Ryu also said a missile launch would require more sophisticated technology, and would not take place from a fixed, openly visible station.
"No country in the world would want to launch a ballistic missile from such an open site," he said.
Ryu said he could not provide any answers to questions about whether North Korea is planning a third nuclear test.
None of Ryu's points rule out the use of the launch, with or without a satellite on top, as a test for developing missiles. The United States and its allies suggest that even though the North may launch a satellite this time, the rocket technologies involved can easily be applied to missiles.
Effective long-range ballistic missiles do tend to use solid fuel, particularly when launched from mobile units, but that does not rule out using a liquid-fuel launch vehicle for a ballistic missile. The first ballistic missiles, Nazi Germany's V-2, were liquid fuel and several countries, including Iran, still use liquids.
This week's satellite launch from a new facility in the hamlet of Tongchang-ri on North Korea's west coast would be the country's third attempt since 1998. Two previous rockets, also named Unha, were mounted with experimental communications satellites and sent from the east coast.
North Korean officials say the 2009 satellite reached orbit, citing Russian confirmation. But the U.S. North American Aerospace Defense Command said Kwangmyongsong-2 did not make it into space, and shortly after the launch, the Interfax news agency quoted an unnamed senior Russian military official saying the same thing.
The third rendition will be North Korea's first working satellite, and is designed to transmit data to the Agriculture and Transportation ministries, said Paek Chang Ho, head of the North's Central Satellite Control Center.
However, Brian Weeden, a technical adviser at Secure World Foundation and a former Air Force officer at the U.S. Space Command, said he doubted the launch would succeed in sending a satellite into orbit. He speculated that the end goal is to test and develop their ballistic missile program.
The planned launch is a highlight of two weeks of celebrations to mark the 100th anniversary of Kim Il Sung's April 15th birthday and the 80th anniversary of the founding of the Korean People's Army.