North Korea’s successful rocket launch on Wednesday underscores considerable progress in its ballistic missile technology, a core part of its controversial nuclear program that threatens its potential adversaries.

Despite international condemnation and sanctions, the North has pushed to enhance its delivery capability to bolster what it calls “nuclear deterrence against hostile forces” including the U.S.

The three-stage Unha-3 rocket fired this week is presumed to have a range of more than 13,000 km, enough to cover the whole of the U.S. mainland.

“The burn-out time for the propellant of the first stage rocket was 156 seconds, 26 seconds longer than the rocket fired in April. Thus, the calculation based on the time indicates the range is over 13,000 km,” a Seoul military source said, declining to be named.

The rocket succeeded in putting what it argues was a satellite into orbit and its second stage rocket travelled about a distance of 2,600 km and fell into waters near the Philippines as projected, Seoul officials said.

The successful launch indicates Pyongyang, which has focused on the development of the long-range rocket since the 1970s, has obtained the core delivery technology to separate each stage of the three-stage rocket, experts noted.

In the 2009 launch, the rocket failed to separate into its third stage, although it traveled some 3,800 km from the launch site. In the 1998 launch, the third stage was not separated, but the rocket flew some 1,600 km.

The proper, timely separation of each stage of an intercontinental ballistic missile is crucial to put a payload into orbit or hit an intended target. Since it fired its first multiple-stage rocket, called Taepodong-1, in 1998, the North has sough to upgrade the technology.

To complete its nuclear weapons program, the North should also enhance its technology to miniaturize warheads. Experts say if the North succeeds in reducing the weight of a warhead to 500 kg to 1 ton, it could build a missile with a nuclear warhead capable of reaching the U.S. west coast.

To refine the warhead-related technology, Seoul believes that the North carried out experimental high-explosive detonations over 100 times. It also believes that the North might have made much headway following its nuclear tests in 2006 and 2009.

Observers argue that the North might also be nearing completing technology to maneuver the direction of a missile after lift-off with assistance from Iranian technicians. Iran is known for its advanced long-range rocket capability.

Another important technology concern is the reentry of the rocket. As the intercontinental missile reenters the earth at a speed of Mach 20, it should be capable of withstanding temperatures of around 6,000-7,000 degrees Celsius. Observers believe that the North might have reentry technology for mid-range missiles by now.

The missile gap between the two Koreas is known to be big as Seoul had been limited to developing ballistic missiles with a range of up to 300 km until the revision of a missile guideline in October.

The North succeeded in test-firing a Rodong ballistic missile with a range of 1,300 km in 1993. It has already deployed its longest-range ballistic Musudan missile with a range of 3,000-4,000 km since 2007. The Musudan, in theory, brings Guam, a key U.S. strategic base in the Asia-Pacific region, within its range.

The Taepodong-2 missile is the North’s longest missile under development. It is presumed to have a range of more than 6,700 km, enough to hit parts of Alaska, but still short of reaching the U.S. mainland. 

By Song Sang-ho (sshluck@heraldcorp.com)