China had recently test fired the mobile, MIRV capable DF-41 missile which is reported to have a range of 14000 km. This missile adds to the existing ICBM inventory of the Second Artillery, which already operates the older DF-5A and the more mobile DF-31, DF-31A. Among the existing three variants the DF-31 with a range of 7200 to 8000 km can reach only till Alaska with a single warhead. The other two have the range to deliver a single warhead on any part of the US mainland. The DF-31A is reported to be MIRV capable and can be armed with three warheads, but this will compromise the range of the missile, making it incapable of reaching the US mainland.
To date, China has the capability of delivering a single warhead per missile on the US mainland. However, it is concerned about a new threat that degrades its deterrence capability—the US missile defence initiatives which continue to improve technologically and expand spatially. And the recent testing of the DF-41 which is capable of delivering 10 warheads over a distance of 14000 km is an effort towards improving the Chinese deterrence capability. China is actively working to balance the equation with the United States to maintain deterrence.
China is estimated to possess 30 to 40 ICBMs1 that have the range to reach the US mainland. In the event of a US first strike, the surviving missiles when launched could be intercepted by the US missile defence systems thus degrading China’s retaliatory capability. Nevertheless, the US Ballistic Missile Defence (BMD) technology has not fully matured and various technical analyses of the US BMD systems tell us that it will be ineffective against saturation attacks and those that come with countermeasures and Multiple Independently targetable Re-entry Vehicles (MIRVs).
It is well known that China has the technology to develop and deploy MIRVs and countermeasures to penetrate defences. In light of this, many analysts believe that China will continue to maintain a minimum deterrence policy and a smaller force structure while improving only the survivability and effectiveness of its delivery mechanisms. On the other hand, considering the improving US missiles defences, it is possible that, in future, China will be forced to go for a vertical increase in its nuclear force (warheads and missiles).
The recent testing of the DF-41 is an indication of the Chinese efforts towards this end. But to further explore this possibility it is essential to study the present US missile defence efforts and the future progress in US missile defence technology and the possible options for China to counter these efforts.
US Missile Defence Efforts
The United States has begun to forward deploy its missile defence component to protect the US mainland from missile attacks. Recent reports state that it will deploy an X-band radar in southern Japan as part of its missile defence plans. Japan already has one X-band radar deployed at Shariki base in Tsugaru City, in the far north of the main island of Honshu.2 The United States would also deploy floating Sea Based X-band (SBX) radar in the Pacific (may be in the North Pacific) for mid-course defence against InterContinental Ballistic Missiles (ICBM). A GBR-Prototype (GBR-P) X-band radar is located at Kwajalein Atoll in the Southern Pacific. An upgraded AN/FPS-115 radar (UHF) is deployed at Beale Air Force Base, California which is supported by an upgraded radar at Flyingdales, UK and Thule, Greenland.
Added to this, the United States along with Japan has also deployed some Aegis SM-3 equipped ships near Chinese waters. These Aegis systems have S-band primary radar and X-band engagement radars and are capable of intercepting ballistic missiles of all range with unitary and separating warheads in its terminal phase, except ICBMs. Apart from providing terminal defence against Short Range Ballistic Missiles (SRBM) and mid-course defence against MRBMs and IRBMs, these systems can detect and track ICBMs and transmit necessary target details and trajectory information to other systems in the BMD architecture for mid-course interception of ICBMs.
In addition to these sensors the United States has deployed space based tracking and surveillance systems which consist of two satellites (technology demonstrators) that scan for targets in the infra-red and visible regions of the spectrum. These space based sensors can detect missiles in their boost phase when they emit high intensity short-wave IR radiations and can transmit information to other sensors and fire control systems.
These multiple arrays of sensors, which are netted together with the Fire Control System (FCS), and at places overlap in coverage, indicate that the detection, tracking and to some extent Decoy-Warhead (DW) discrimination capability of the United States is highly advanced, particularly for the crucial mid-course phase. All US radar sensors, except early warning radars AN/FPS-132 (UHF), Cobra Dane radars (L band) and the SPY-1 radar (S-band), operate in the X-band region, which helps in obtaining high resolution target details, thus enabling the discrimination of decoys and other missile debris from actual warheads.
However, an attacker could employ both Infrared (IR) and radar signature countermeasures. Hence, for better Decoy-Warhead (DW) discrimination, the early warning and tracking systems should include optical sensors as well. The space tracking and surveillance system, which is in the demonstration phase, would be improved and expanded in future enabling it to perform better tracking as well as DW discrimination in the optical region thereby enhancing the effectiveness of the BMD systems. The forward positioning of the ground based sensors along with the space based systems would provide more reaction time for the fire control system.
The improvement in the DW discrimination and the early initiation of the interception process will enable the employment of Shoot-Look-Shoot method, which would reduce the number of interceptors required and also lessen the burden for the terminal defence systems.
The other vital area which needs refinement is interception technology. The kinetic kill vehicle of the mid-course interceptor uses a dual band (visual and IR) optical terminal seeker5 to home in on to the warhead. To increase the accuracy as well as terminal target discrimination efficiency, which would improve the Single Shot Kill Probability (SSKP) of the interceptor, a dual seeker (optical and high frequency Imaging Radar) might be used in the future. A higher SSKP would further reduce the number of interceptors required. Improvement to the burn-rate performance of the rocket motor, which would increase the average speed, and upgrading of control systems with better onboard software and attitude controls could be expected in future. All these improvements and fine tuning will complicate the Chinese efforts to maintain credible deterrence.
US BMD vs. Chinese Nuclear Force
A Chinese ICBM attack on the US mainland could be launched from two directions; either, over the North Pole (Circumpolar trajectory) or, over the extreme fringes of the Northern Pacific.6 Along both these directions, the missiles have to pass through the engagement envelope of the interceptors based in Alaska and, depending on the target area, over California too. The US BMD sensors (ground based X-band radars and Aegis ships) in and around Japan would detect and track any Chinese ICBM launch during the boost phase.
It has been reported that AN/SPY-1 radars have tracked ballistic missiles at ranges in excess of 1000 km and the THAAD GBR (AN/TPY-2) X-band radar may be used as forward based sensors to alert the SM-3 systems when a threat missile launch has been detected.8 However, the altitude (boost phase) at which the missile would be detected depends on the distance of the launch point from the radar (due to Earth’s curvature and line of sight issues).
If the missile is launched from areas closer to the shore, within the engagement envelope of the SM-3 missile, it is possible that the ICBM will be intercepted in the boost phase itself (To perform boost phase interception, interceptor speed might require improvement, minor changes in the guidance software might also be required, and the target missile with the presence of booster stages will also present a large target for the X-band radar.)
Over the next 10 to 15 years, the US military wants to equip Aegis ships with a much larger, faster interceptor that the United States is developing cooperatively with Japan. Estimates suggest that the interceptor's speed will be high enough—in principle—to allow it to intercept missiles with intercontinental range.9 Therefore, there is a high probability that the missiles would be launched from deep inland China and in the circumpolar trajectory to avoid the Aegis system. Operating from deep inland would also increase the survivability of the missile units from US air strikes. To penetrate an effective BMD system, the Chinese missile should employ appropriate counter measures (decoy with IR and radar countermeasures, Manoeuvrable Re-entry Vehicle (MARV) and MIRV).
However, with the gradually increasing capability of the US Decoy-Warhead discrimination capability, the countermeasures would gradually continue to become less effective. China does not enjoy the option of launching its land based ICBM in depressed or lofted trajectories to overwhelm the defences, as it would reduce the range of the missile, thus preventing them from reaching the US mainland.
Currently, China has deployed two ICBMs: the silo based older DF-5A and the solid fuelled and more mobile DF-31A. China had earlier tested the longer range, road mobile DF-41 with a range of 14000 km. While the DF- 5A and the DF-31A are reportedly single warhead10 missiles, the DF-41 will be a MIRVed (10 warheads)11 missile. At present, there are an estimated 30 to 40 ICBMs that have the range to reach the United States and, each being a unitary warhead missile, the total number of warheads would be 30 to 40. Assuming a SSKP of 0.30 per cent for the interceptors based in Alaska and California, it would require four interceptors for a single warhead. Hence the total requirement would be of 120 to 160 interceptors.
But once the MIRV (10 warhead) capable DF-41 becomes operational, the number of warheads for this missile force would be a multiple of 10, thus quadrupling the number of interceptors required. This will get more complicated if the Chinese deploy decoys and countermeasures which would further increase required interceptor numbers. However, as discussed earlier, the improving sensor capability for Decoy-Warhead discrimination and the interceptor efficiency might reduce the number of interceptors required, negating the Chinese efforts to some extent.
The other measure the Chinese could undertake to counter US efforts would be to strengthen their undersea deterrence. Submarine Launched Ballistic Missiles (SLBM) are a little difficult for missile defence systems to counter compared to land based missiles. A submarine could fire its SLBM in a depressed trajectory confusing the tracking systems and reducing the reaction time for the BMD system to respond. China’s SSBN fleet is in a nascent stage with all nuclear ballistic missile submarines (SSBN) (Xia and Jin) tied up at ports with zero patrols so far due to various technological problems.
Once these problems are overcome and the boomers (Jin class) are operationalised, it will ensure better deterrence. Considering that four Jin class SSBNs will be deployed, with each housing 16 JL-2 missiles, it makes a total of 64 missiles and warheads (if armed with a single warhead). The JL-2 can also be MIRVed (three warheads (60, 90 or 120 kt)12 ), multiplying the total number of warheads to 192. However, an effective Chinese under sea deterrence, given the various problems (technology, crew training and experience), does not appear possible at least in the near future.
The US efforts to improve and expand its BMD system would degrade Chinese nuclear retaliatory capability thus making China’s nuclear deterrence less effective. This would force Beijing to initiate efforts to go for a qualitative and quantitative improvement of its nuclear force by increasing and improving its nuclear force structure by deploying more ballistic missiles with MIRV and MARV capability and penetration aids. China’s emphasis on the land based deterrent component is evident from the recent testing of the MIRV capable DF-41.
This missile offers sufficient range to target any part of the US mainland and is also MIRV capable, which will be more effective in penetrating the missile defence shield being deployed by the United States. The deployment of the DF-41 will result in a vertical increase in the nuclear force operated by China. Nevertheless, the minimum deterrence doctrine might not change, with the aim remaining the same, i.e. to operate a necessary force capable of delivering at least a few warheads on the US mainland.