North Korean Musudan IRBM Failed – Again


The defence ministry in Seoul said the missile test took place at around 5:20 am on Monday near the eastern port city of Wonsan. The missile likely a Musudan Intermediate-range Ballistic Missile (IRBM) was launched from a mobile transporter-launcher, and flew for seconds before exploding, the official said.

In April, the North failed three times to test-fire a Musudan. Tuesday’s launch appears to have been its first missile test since then, and experts said it was unusual to test-fire a missile so soon after a failure.

Musudan that has been declared ‘operational’ is capable – theoretically – to hit targets at ranges up to 4,000 km (2,500 miles). With the credible performance, this weapon represents the rough state’s highest threat to the region, as it can hit targets far beyond South Korea, in Japan as well US bases in the Pacific, including Guam.

“North Korea shows no sign of abandoning the development of nuclear missiles, and so we will continue to work closely with the U.S. and South Korea in response and maintain a close watch,” Japanese Minister of Defence Gen Nakatani told a media briefing.

Pyongyang has not tested the Musudan missile in flight since its inception in 2003. Analysts estimate North Korea may have produced 50 such missiles. Their public debut in 2010 indicated the induction of 31 such missiles with North Korean strategic forces. 19 such missiles were reportedly transferred to Iran, where it is designated BM25.

It appears to be the latest in a string of missile tests as the country tries to advance its weapons program in defiance of the international community and its closest regional ally, China. Neither Iran, nor Pyongyang have tested these missiles before 2016, nor did they validate their full range in flight.

The Musudan uses a propulsion system derived from the proven system that powers the Russian SS-N-6 Submarine-Launched Ballistic Missile (SLBM). Therefore, given that manufacturing process and subsystems are reliable, the Korean missile would also perform as expected since this propulsion system proved its reliability in 461 successful launches of the Russian ‘R27 Zyb’ SLBM.

However, this was not the case. The Korean developers probably suspected their system was not mature enough to take the challenge. Intelligence sources reported in 2013 on a previous aborted launch of the missile.

Assuming that the Korean missile engineers have retrieved missile parts after the explosions, and gathered flight data by telemetry, indicating the system’s failure dynamics during the flight, Western analysts expect they would be able to identify the causes of the failures, and improve the system’s reliability. However, compressing four test attempts in less than two months means they have not had enough time to assess their findings and implement adequate solutions.

When the Musudan/BM25 eventually reaches maturity, it is likely become a much bigger concern for countries in the Far East, MiddleEast and Eastern Europe, as all rest within its reach.

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[ismember]While the design of the Musudan/BM25 missile is clearly derived by the Russian R27, the source of subsystems used in the missile has not been clear. Analysts assess Pyongyang could have reverse-engineered the system, designed it indigenously with Russian support or managed to receive a number of key elements for the system. The repeated failures with Musudan launches could indicate reverse-engineering or indigenous designs that require a long learning curve, particularly given the unique attributes of this unique weapon system.

The Koreans are using a proven propulsion system, backed by know-how and support provided by the original system designer (Makeyev OKB). That’s why Western analysts attribute the repeated failures to manufacturing issues rather than design flaws. The R27/4K-10 weapon system that provides the baseline for Musudan/BM25 has been successfully tested 461 times through its service life. The North Korean variant was slightly modified from the original design, adding larger propellant tanks while reducing the payload from three reentry vehicles to a single warhead.

As a submarine-launched ballistic missile, the R27 was the first sea-based liquid-fuel missile system. As such, it was designed to be as compact as possible and sustain extended storage of fuelled missiles in submarines. The propulsion system uses unsymmetrical dimethylhydrazine (UDMH) as fuel, and nitrogen tetroxide (NTO) as oxidizer – a modern, highly energetic liquid propellant. The single-stage missile has an all-welded envelope and its propulsion system is embedded inside the fuel tank. The R27 was fueled by the manufacturer and loaded to the submarines prior to their patrol mission and it is likely the Korean derivative uses a similar process.[/ismember]