By Michael Elleman, Consulting Senior Fellow for Regional Security Cooperation, IISS-Middle East
North Korea has again defied the international community by launching a small satellite into orbit using a large, domestically assembled rocket. The launch violates a series of United Nations Security Council resolutions, which proscribe North Korea’s use of ballistic missile technologies. The UN Security Council met in New York to condemn Pyongyang’s action and punitive sanctions will soon be imposed.
The firing of a large, three-stage Unha rocket is without question a provocation worth condemning. Pyongyang must be punished for violating its UN obligations, if for no other reason than to raise the costs and deterring future tests of its nuclear bombs or long-range missiles. However, when judging the strategic consequences of the satellite launch, the context is paramount.
The Unha satellite launcher is ill-suited for use as a ballistic missile. Further, additional firings of the Unha will not play a significant role in advancing North Korea’s long-range ballistic-missile development efforts. Given the finite political, diplomatic and economic tools available to punish Pyongyang, the international community, led by the US, must identify strategic priorities. Imposing sanctions to deter future satellite launches must take a back seat in relation to efforts designed to prevent North Korea from exporting nuclear technologies, detonating nuclear bombs, and flight testing the KN-08, Musudan and other long-range ballistic missiles.
The Unha satellite-launch rocket is not a ballistic missile
The Unha is a liquid-fuelled rocket powered by engines originally developed in the former Soviet Union, and most likely manufactured in Russia and imported by Pyongyang. The rocket’s first stage houses a cluster of four Nodong engines, while the second stage is a modified Scud missile, with a larger diameter fuselage to carry more propellant. The third stage employs verniers, or steering engines, scavenged from either a retired Soviet R-27 (NATO designated SS-N-6) submarine-launched ballistic missile, or possibly the ROTA, a short-range missile developed but never fielded by the Soviet military.
As with previous firings of the Unha, the rocket’s configuration and flight trajectory were fully consistent with a satellite launch, though the first launch in 2006 exploded too soon after lift-off to determine its trajectory and mission. The Unha’s flight path levelled off once the rocket reached its orbital altitude of just over 400 kilometres and continued to accelerate the payload along a route nearly parallel with the earth’s curvature to achieve the radial velocity needed to sustain the orbit. The relatively low-thrust Scud and vernier engines used by the second and third stages, respectively, are ideally suited for the mission.
Ballistic missiles, on the other hand, climb to great altitudes while simultaneously accelerating the payload down range. An intercontinental ballistic missile, or ICBM, travelling on an optimised trajectory will typically reach altitudes of 1,000km or more before descending back to the earth’s surface. To achieve maximum results, ballistic missiles are powered by high-thrust engines to reach the required altitude while minimising gravity losses. The Unha would sacrifice roughly 800km of range because of gravity losses if it flew as a ballistic missile using the low-thrust Scud and vernier engines.
Indeed, if one examines the history of early long-range missile development in the Soviet Union, US, China and France, one finds that none of these countries transformed a satellite-launch rocket into a ballistic missile, while the opposite was common. The first satellites launched into space, by the Soviet Union and the US, were carried by modified ballistic missiles, the R-7 and Jupiter-C, respectively. China developed its first long-range missiles in parallel with its satellite launch rockets. The two systems shared many major components, including the primary rocket stages. However, even while China pursued satellite launchers and missiles in tandem, the ballistic missiles still underwent a full flight trial programme stretching over many years.
The primary reason no country has modified a satellite launcher for use as a ballistic missile is because the two missions have very different operational requirements. A satellite launch is typically prepared over a period of days if not weeks. Engineers assemble and fuel the rocket a few days before the planned firing. They can check and re-check the assembled components and individual mechanisms prior to launch, and if the weather conditions are unfavourable, the firing can be delayed. Additionally, if a component malfunction is detected prior to lift-off, the launch can be delayed, systems checked and fixed, and the countdown resumed.
Ballistic missiles, on the other hand, like most military systems, must be able to perform at the push of a button, under any weather condition, day or night. The military requirements dictate that the missile undergo flight tests under a variety of operational conditions to validate performance and reliability. Historically, the development process mandates at least a dozen, if not many more, test launches before the missile can become operational.
Even if North Korea were to transform the Unha rocket by replacing the second- and third-stage propulsion systems with higher-thrust engines, a full development effort, flight tests would have to be conducted. In addition, engineers would have to create a heat shield to protect the payload from the rigours of re-entry into the atmosphere. More importantly, perhaps, because of the Unha’s immense size and mass, it would be difficult if not impossible to deploy the 90-tonne missile on a rail car or lorry. Without mobility, an Unha ballistic missile would be highly vulnerable to prelaunch attacks. North Korea’s limited strategic depth and antiquated air defences would be little match for an advanced, airborne reconnaissance-strike force, such as that fielded by the US and others in the region.
This is presumably why North Korea is developing the Musudan and KN-08 long-range missiles, which can be deployed on mobile launch vehicles. Prototypes of the two missiles have been showcased during military parades over the past few years. However, neither missile has been test flown.
Setting strategic priorities
Having never flight tested the Musudan and KN-08, Pyongyang has no measure of their respective performance and dependability. Threatening to use or indeed firing the untested missiles would be a risky adventure. During their first ten test flights, first- and second-generation, long-range ballistic missiles developed by the Soviets, Americans, Chinese and French failed more often than they succeeded. The Unha failed on its first four firings. Thus, Pyongyang would have to assume great risk of failure if it threatened to launch or fired the KN-08, Musudan or other long-range missile before it had validated its reliability. It is, therefore, highly unlikely that Pyongyang would elect to fire its unproven missiles except under the direst of circumstances, such as the regime coming under direct military threat by a foreign army.
Stopping North Korea from testing and developing a viable, long-range ballistic missile must be a strategic priority, second only to preventing it from transferring nuclear material or technology, and detonating additional nuclear bombs. If North Korea succeeds in developing the KN-08, or equivalent, it could threaten the US mainland and erode Washington’s long-standing extended deterrence commitments to South Korea, Japan and other regional allies. Deterring future satellite launches is important, but not at the cost of preventing long-range missile tests.