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The effects of NMD on Chinese strategy
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| 7 March 2001 |
Dr Li Bin is associate professor and director of the Arms Control Program, Institute of International Studies, Tsinghua University, Beijing.
THE
PLANNED deployment of the US National Missile Defense (NMD) system is viewed
by China as a threat to its national security and a destabilising initiative
that may force China to alter plans for the modernisation of its own nuclear
arsenal. How exactly NMD will affect China's nuclear strategy is currently unclear but some judegements can be made based on a quantitative understanding of how China's nuclear deterrent currently works.
China's nuclear forces were developed to defend the country's national security interests against the possibility of nuclear blackmail. Initially, China possessed only a symbolic nuclear deterrence with no real capability to retaliate, but from 1980, when China acquired the ability to launch inter-continental ballistic missiles (ICBMs), its deterrence has been based on the quantitative ambiguity of its nuclear force rather than the size of its arsenal.
The two dozen Chinese land-based ICBMs that have been detected and located by US intelligence agencies would have very little chance of surviving a US preemptive nuclear strike. However, because China has neither confirmed nor denied any US estimates of its ICBM strength, it is difficult for the USA to rule out some margin of error. In its current nuclear strategy the possibility of a few undetected Chinese ICBMs being launched in retaliation is considered enough to deter the USA from attempting a pre-emptive nuclear strike against China. Thus, it is the uncertainty of US estimates, rather than the total number of Chinese ICBMs, that is directly relevant to the credibility of Chinese deterrence in its current form.
Now, however, China is about to enter a new stage of nuclear development, in which it aims to acquire a deterrent capability that does not rely on uncertainty to be effective. In this stage, no matter how well the USA measures the total number of Chinese nuclear weapons, at least a few Chinese ICBMs or submarine-launched ballistic missiles (SLBMs) would survive a US pre-emptive strike and could be used to retaliate. This improvement in China's deterrent capability is designed to avoid any uncertainty in external perceptions of its ability to retaliate to a pre-emptive strike.
To achieve its aim, China can either increase the quantity or raise the survivability of its nuclear arsenal.
Table 1 shows that if China does not improve the survivability of its missiles, beyond placing them in hardened silos, it will require a large expansion of its arsenal. If, on the other hand, China successfully develops mobile ICBMs or SLBMs, it needs very little, if any, increase in its long-range nuclear force.
Reports indicate that the size of the Chinese long-range nuclear arsenal has remained stable over the last two decades and that China is working on mobile ICBMs. This suggests that China has chosen to pursue survivability rather than expansion. If there is no deployment of a US NMD system, this is likely to remain the case. It is predictable, stable, and will increase Chinese security without increasing the perception of a Chinese threat in other countries. However, NMD deployment would force China to consider adopting approaches that would help defeat that defence and this would introduce much greater uncertainty into the direction of its modernisation programme.
According to its current plan, the USA will deploy NMD in several phases. In the first development phase, sometimes referred to as Capability One (C1), it will deploy one hundred interceptors in Alaska, upgrade existing early warning radars, and deploy a new X-band tracking radar. The goal of this phase is said to be to defend against an attack by a few tens of missiles with, at best, simple countermeasures. It is noteworthy that the C1 system was originally designed to have twenty interceptors and to deal with a few ICBMs. Its proposed size and capability was subsequently enlarged to its current level.
In later phases, the USA plans to deploy more radars, low-orbit and high-orbit missile-tracking satellites, more interceptors and would add a new launch site. The stated goals of these phases are to defend against a few tens of missiles with complex countermeasures.
The number of missiles the C1 system is intended to defend against is comparable to the reported size of the whole Chinese ICBM force and is obviously larger than the number of Chinese retaliatory ICBMs. Thus, even a very thin NMD system with very few interceptors would pose a serious threat to China's retaliatory capability.
No matter how the US government clarifies its intentions in deploying NMD, many Americans still believe that a NMD designed for 'rogue states' would have an inherent capability to defend against Chinese ICBMs. China fears that if the USA believes that a first nuclear strike plus a NMD system could render impotent China's nuclear retaliatory capability, the USA might become less cautious during any crisis involving China.
NMD deployment would therefore disturb the strategic stability between China and the USA and increase the risk of conflict.
China's arms control representative, Ambassador Sha Zukang, has said "it is evident that the US NMD will seriously undermine the effectiveness of China's limited nuclear capability from the first day of its deployment. This can not but cause grave concern to China."
The structure of the NMD system designed for the Clinton Administration is clearly East Asia-oriented. In the C1 phase, the only new missile tracking radar will be deployed on Shemya, an outpost well located to watch missiles from East Asia, including Russian Siberia, North Korea, and China. The only NMD launch site in the C1 and C2 phases would be in Central Alaska, which is much closer to East Asia than the Middle East or European part of Russia. This geographical structure provides more time and less required defence range for the interceptors in defending against missiles from East Asia than from other places in the world. This may help the USA take a strategy of 'shoot-look-shoot' in defending against missiles from East Asia. This strategy could raise the kill probability of the NMD system and allow it to operate more efficiently. Thus, the East Asia focused structure of the NMD system could leave the USA with a strong impression that missiles from East Asia would have little chance to penetrate US defences.
The intention behind NMD is also a concern to China. As the relations between North and South Korea are improving, the voices in the USA calling for aiming the NMD at China are getting stronger. This will cause serious concerns in China and the Chinese will have to explore possible responses in their nuclear development if the USA decides to deploy NMD.
China is now using its diplomatic resources to influence the USA on NMD deployment. The hope is that the USA will take China's security concerns seriously when it considers NMD deployment. If not, China will seek to develop other approaches in order to maintain the effectiveness of its nuclear deterrence. Any such approaches would need to meet four fundamental requirements.
Above all, the direction of future developments must be feasible in helping defeat the US NMD. Judging the feasibility of proposed approaches is difficult because the Ballistic Missile Defense Organisation (BMDO) has declared that the NMD system would be able to defeat simple and complicated countermeasures as its development proceeds and it is not clear how it would do this based on the proposed technology. Also, although the technology involved in the NMD plan proposed by the Clinton Administration was clear, the plan may change under the Bush administration. Furthermore, China needs to worry about any scientific surprises in NMD development. Finally, different organisations in the Chinese defence industry may have different assessments of the feasibility of different approaches. Due to this kind of uncertainty, the Chinese government may want to pursue more than one set of approaches in case one does not work.
Some of the Chinese approaches should be visible to the USA so that they will know that their NMD system will not be able to counter China's retaliatory capability.
Since the Chinese government's priorities lie in economic development, it is important that nuclear modernisation does not become a financial burden. Hence affordability will be a central consideration.
It is also important that the chosen course to modernisation should not increase the perception of China as a threat to other countries. China is now in the process of participating more fully in the international community and it needs a peaceful environment for its economic development. China would prefer moderate approaches while avoiding others that would have greater negative consequences in arms control or that would lead to new tensions.
In addition to these key requirements, there are some additional factors that could also influence the Chinese government's decision.
- Decision makers will prefer approaches that are compatible with each other. However, decision makers may want to see some competition among incompatible approaches in the early part of the development process. Therefore, incompatible approaches may not be excluded in the early Chinese plans.
- Some precautionary approaches are also needed. The BMDO declares that NMD will defeat simple and complicated countermeasures in different development phases. It is not clear how the current NMD technology will do this. So the Chinese would have to worry about some possible scientific surprises. Also some people in the USA are pushing for stronger missile defences or even a revival of part of the Space Defense Initiative (SDI) programme, thus China may want to make some technical preparations to deal with a stronger missile defence.
There are four possible approaches to defeating NMD. The first aims to overwhelm the defence by building more ICBMs, placing multiple independently-targeted re-entry vehicles (MIRVs) on existing ICBMs to multiply the number of warheads; releasing decoys from the missiles; or dispersing chaff to fool the sensors on interceptors.
The second aims to lower the observability of warheads by applying radar or Infrared stealth technology.
The third group creates a rivalry between the warheads and the interceptors during flight by making warheads maneuvre or through other means.
The fourth raises the survivability of ICBMs by deploying mobile ICBMs and/or SLBMs; building a missile defence; or putting nuclear weapons on hair-trigger alert.
If China aims to overwhelm NMD by developing more warheads, the size of its retaliatory force should be larger than the sum of the number of warheads intercepted by the defence and the number of warheads that can produce 'intolerable damage'. Here we assume that two interceptors are used to kill one warhead, so that a C1 system with 100 interceptors is able to kill 50 warheads.
Table 2 gives the number of warheads China needs to overwhelm C1 or C2 systems. This suggests that it is not economic or efficient for China to enlarge its silo-based nuclear force in response to NMD deployment. It would be a more sensible option for China to overwhelm NMD with fully mobile ICBMs or very survivable SLBMs when these technologies are ready.
A key problem here is the timing. If China goes for a strategy of overwhelming NMD with an enlarged nuclear force, it will need to develop mobile ICBMs or SLBMs before the USA finishes the deployment of NMD. This may not be feasible and thus China might need to revert to a massive expansion of its ICBM arsenal.
Enlarging its nuclear forces could damage China's international reputation and could involve a significant financial burden. It might also require the production of additional fissile materials for new warheads, especially if China chooses to add silo-based ICBMs. If China needs to keep the option of such a build-up open this would make it reluctant to join a Fissile Materials Cut-off Treaty (FMCT).
Although the costs could be large, the build-up option cannot be ruled out. It is mathematically simple to understand and certain to work and thus, in Chinese debate, would win some support from non-technical people. Another advantage is that the build-up would be visible to the outside world and would therefore help discourage any first strike against China.
An efficient way to enlarge a nuclear force is to 'MIRV' missiles. However, for China, MIRVing its silo-based ICBMs is not a good idea because its nuclear force is much smaller than Russia's. MIRVing the survivable ICBMs could be better, but this depends on whether the technology is mature.
Some Chinese articles mention multiple-warheads being used as countermeasures and these probably refer to missiles with one real warhead plus many decoys. As discussed in a report made by US scientists from the Union of Concerned Scientists and the Massachussets Institute of Technology (UCS/MIT), the proposed NMD sensors cannot differentiate real warheads from decoys during the mid-course of flight.
The development of such technology is within China's capabilities. This means that the deployment of decoys is a much more efficient and simple way than the use of MIRVs for China to defeat the NMD system.
Stealth technology can be used to make warheads less observable. For example, the radar reflection of a warhead can be reduced by putting the warhead in a reentry vehicle with a pointed cone-sphere shape or painting the reentry vehicle with radar absorbing materials. This countermeasure is based on fairly uncomplicated technology and can reduce the effectiveness of the defence. Another stealth technology, which is discussed in the UCS/MIT report, is to reduce the infrared radiation of the warhead by cooling its skin. This countermeasure is also based on achievable technology and can help defeat the defence.
The only countermeasure so far mentioned by the Chinese defence industry is the use of a maneuvring warhead.
The maneuvre capability of the warhead should be comparable to that of the interceptor, so the warhead needs to detect the approaching interceptor and start its maneuvre at an appropriate time; otherwise, the warhead needs to carry a lot of fuel so that it can maneuvre continuously. Either option is a challenge to warhead designers. The first requires very capable sensors on the warhead that can search approaching interceptors from all possible directions, while the latter needs a considerable reduction in the weight of the nuclear device so that the re-entry vehicle can carry additional fuel and an engine.
To match the maneuvre capability of the interceptor, the warhead may also need a new design to tolerate off-axis accelerations during maneuvres. This may require new nuclear tests and therefore create difficulties for China in ratifying the Comprehensive Test Ban Treaty (CTBT).
Raising the survivability of Chinese nuclear weapons cannot directly defeat NMD, however, it can make some other approaches much more effective and efficient. For example, China would need many fewer nuclear warheads to overwhelm NMD if China can deploy survivable ICBMs rather than silo-based ICBMs. In any case it is the main goal of Chinese nuclear modernisation to build a survivable mobile and/or sea-based nuclear force.
Some point missile defences protecting missile silos may also help raise the survivability of Chinese ICBMs. However, the technology is very challenging and the cost is very high.
Another approach to increasing nuclear weapon survivability is to put Chinese nuclear weapons on hair-trigger alert. In this case, China would need to launch its nuclear weapons after it detects a nuclear attack but before incoming nuclear weapons arrive. This strategy is called "launch on warning" and was cited as a reason for not fearing an NMD system by American negotiators in their consultations with Russia over the Anti-Ballistic Missile (ABM) Treaty. This approach requires advanced and reliable early-warning systems, which China does not, as yet, possess.
All these approaches and maybe some others are being considered by Chinese decision makers. Deciding on a particular course of action will be difficult because of the many factors that need to be taken into consideration, and the uncertainty involved means that the future development of Chinese nuclear deterrent is highly unpredictable.
Some of the approaches that the Chinese government will need to consider are likely to cause problems for Chinese participation in arms control. For example, China may need some additional fissile material if it needs to build more nuclear weapons, especially silo-based ICBMs.
Even if China does not opt for a build-up strategy it will be difficult for China to accept a FMCT that puts a ceiling on the size of the Chinese nuclear force and loses China an option for countering NMD.
In China, there have been some arguments that China lost too much in signing the CTBT. If some Chinese feel that more nuclear tests are required to develop countermeasures like the maneuvring warhead discussed above, voices opposing the CTBT would certainly become stronger in China.
In the non-proliferation arena, China would become less interested in legally incorporating the Missile Technology Control Regime (MTCR) and its annexes into its export control law if the USA does not echo China's concern over NMD. The USA would become less influential in dissuading China to cut its co-operation with some countries if China believes that such co-operation is consistent with existing international law. In the area of nuclear disarmament, the NMD will also become a new and serious obstacle that blocks China from considering joining global nuclear reduction efforts.
Dr Li Bin will be speaking at the forthcoming Jane's Missile Proliferation 2001 Conference, 12-13 November 2001, in Edinburgh, UK. Go to conference.janes.com
| Table 1. NUCLEAR WEAPONS NEEDED BY CHINA FOR CREDITABLE MINIMUM NUCLEAR DETERRENCE UNDER VARIOUS ASSUMPTIONS | ||||
| WARHEADS IN THE USA AT DIFFERENT LEVEL | NUMBERS OF CHINESE WEAPONS AND HYPOTHETICAL DEPLOYMENT | |||
| Silo-based | One-dimensionally mobile | Two-dimensionally mobile | Submarine-based | |
| START II: | 1,200 | 167 | 22 | 30 |
| Operational and hedge | ||||
| ICBM: 1,400 | ||||
| SLBM: 2,130 | ||||
| START II: | 800 | 112 | 18 | 30 |
| Operational only | ||||
| ICBM: 500 | ||||
| SLBM: 1,680 | ||||
| Total: 1,000 | 430 | 57 | 14 | 30 |
| ICBM: 230 | ||||
| SLBM: 770 | ||||
| Source: Li Bin, 'China's Nuclear Disarmament Policy' in Harold A. Feiveson (ed), 'The Nuclear Turning Point' (Brookings Institute Press, 1999) | ||||
| Table 2. NUCLEAR WEAPONS NEEDED BY CHINA TO MAINTAIN CREDITABLE MINIMUM NUCLEAR DETERRENCE IN CASE OF C1 | ||||
| WARHEADS IN THE USA AT DIFFERENT LEVEL | NUMBERS OF CHINESE WEAPONS AND HYPOTHETICAL DEPLOYMENT | |||
| Silo-based | One-dimensionally mobile | Two-dimensionally mobile | Submarine-based | |
| START II: | 1,250 | 217 | 72 | 80 |
| Operational and hedge | ||||
| ICBM: 1,400 | ||||
| SLBM: 2,130 | ||||
| START II: | 850 | 162 | 68 | 80 |
| Operational only | ||||
| ICBM: 500 | ||||
| SLBM: 1,680 | ||||
| Total: 1,000 | 480 | 107 | 64 | 80 |
| ICBM: 230 | ||||
| SLBM: 770 | ||||
| Source: Li Bin, 'China's Nuclear Disarmament Policy' in Harold A. Feiveson (ed), 'The Nuclear Turning Point' (Brookings Institute Press, 1999) | ||||
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| US
Secretary of Defense Donald Rumsfeld has put his backing behind the
deployment of a US NMD system that may prove to be stronger than that
envisaged by the Clinton Administration. (Source: PA News) |
 |
| The
threat posed by the deployment of a US NMD system will force China
to develop new technologies and approaches for its nuclear arsenal.
In this process, Beijing will need to consider all possible manifestations
of the NMD system. Artist's impression of the Exo-atmospheric Kill
Vehicle (EKV), built by Raytheon Systems. (Source: Raytheon) |