North Korea on Wednesday managed to fly its intermediate-range ballistic missile for 400 kilometers for the first time, sparking mixed assessments on its degree of success after its previous five launches went down in supposed failures.

After its first Musudan missile launch at around 5:58 a.m. exploded in yet another failure, the communist state fired another missile about two hours later at 8:05 a.m.

The second projectile’s flight, while well short of the 500 kilometer suspected minimum flight range of the Musudan, was assessed to have managed to sustain flight for a significant range.

The Joint Chiefs of Staff said South Korea and the U.S. are conducting an assessment on the second launch as to whether it can be evaluated as a success.

South Korea and the U.S. condemned the launch as a violation of the U.N. Security Council resolution. The UNSC in March adopted resolution 2270 that encompasses the strongest economic sanctions against Pyongyang to date.

“Not only is the missile launch a clear violation of the UNSC resolution that bans it from conducting any launch using ballistic missile technology, it is a grave danger to the peace and security of the Korean Peninsula and the international society,” said Foreign Ministry spokesman Cho June-hyuck.

“The government strongly condemns it (the launch) and solemnly warns that the North will face even stronger sanctions and pressure by us and the international society.”

The U.S. State Department said it will raise its concerns at the U.N. to hold Pyongyang responsible for the actions.

On the coattails of the launches, Cheong Wa Dae held a National Security Council meeting with the ministers of foreign affairs, unification and defense and the chief of National Intelligence Service to assess the North’s missile technology along with possible responses.

During a meeting with the National Unification Advisory Council, President Park Geun-hye said, “Should North Korea go ahead with an additional nuclear test, the government will deal with it more sternly together with the international community. The North Korean regime must realize that at the end of reckless provocation only awaits complete isolation and self-destruction.”

Musudan has a presumed range of 3,000 to 4,000 kilometers and can put the U.S. base in Guam within its striking range. Deployed for use since 2007, its presence has been a looming threat over Seoul as well as U.S. forces deployed in the Asia-Pacific region.

But its first launch in April -- along with three subsequent ones prior to Wednesday -- have all ended in failures, raising questions about the legitimacy of the Musudan’s capacity.

South Korean military, however, admitted that the North may have made some sort of breakthrough after the series of botched launches.

“We suspect that there has been some progress in the functions of (the missile’s) engine,” said a Joint Chiefs of Staff official.

A government official was quoted by local media as saying that the Musudan had flown 400 kilometers because Pyongyang shot it at a higher degree than usual. This sparked speculations that the North had deliberately reduced the range of the missile so that it will not fly into Japanese territory.

The missile, fired from Wonsan, Gangwon Province, is presumed to have flown toward the East Sea. Military officials confirmed that the missile was shot at a higher degree, but declined to comment on what happened to the missile.

Some officials downplayed the significance of the launch, saying it was a partial success of a random missile that has never actually been fired prior to this year.

“Weapons are usually deployed after a string of test launches, but the Musudan bypassed this process. Just because a few managed not to be blown up, doesn’t mean it is a success,” said a military official.

He added that the repeated launches of the Musudan, despite its failures, may just be an attempt by the North Korean military to cater to its youthful leader Kim Jong-un’s unreasonable demands.

Kim in March ordered his troops to complete a test firing of a ballistic missile that can be armed with a nuclear warhead.

But Kim Dong-yup, a professor at the Institute for Far Eastern Studies, said that the true purpose of the launch may not be to prepare the Musudan for actual use.

Instead, he suspected that the launch is part of a bigger plan to acquire or boast the capacity to conduct a nuclear strike on the mainland U.S.

The reentry vehicle is a critical technology for ballistic missiles. While the North is presumed to have the reentry technology for shorter-range missiles, the military has presumed that it will take some time for Pyongyang to acquire one for the intercontinental ballistic missiles.

ICBMs with a range of over 10,000 kilometers have peak altitude of approximately 1,200 kilometers. Reentry from this height is accompanied by high pressure and temperature that inflict damages to the warhead.

Citing the Japanese Defense Ministry, some news outlets said that the second missile flew to heights of over 1,000 kilometers, which borders the conventional peak altitude of ICBMs. The South Korean military did not confirm the speculation.

“Musudan is merely the means to an end. ... By reducing the range and shooting it higher, it can simulate similar environment as the reentry of the ICBM,” Kim said.

He pointed out that the North has demonstrated many aspects of a nuclear missile, such as engines, solid fuel -- which makes the missiles harder to detect -- a detonating device and nuclear warhead.

“North Korea has been boasting its nuclear capacity, with the outside world not being threatened. This is because it has no reentry vehicle (for the ICBM). Acquiring this will complete the North’s nuclear capacity.”

He said it is too early to determine whether the North’s launch was a reentry test, as he suspects, or if it had succeeded.

“If (the launch) did managed to simulate (the reentry) of the ICBM, it can potentially become a frighteningly significant success.”

By Yoon Min-sik (minsikyoon@heraldcorp.com)