TAIPEI (Taiwan News) — China fired a “carrier killer” anti-ship ballistic missile (ASBM) into the South China Sea on Wednesday (Aug. 26), the day after the U.S. sent a U-2 aircraft to spy on Chinese military exercises.
China's action has already drawn the ire of Japan, undoubtedly increases tensions in the region, and raises a question: just how advanced is this newly developed Chinese weapon?
Most ballistic missiles reenter the atmosphere at around Mach 8 to Mach 15 at an altitude of 50 km, depending on the reentry angle. Due to increasing air resistance in the dense region of the lower atmosphere, after it survives the maximum Q heating period at an altitude of around 15 to 20 km, the missile's terminal speed is reduced to around Mach 2 at 3 to 5 km above the surface, depending on the shape of the warhead.
Therefore, target acquisition and control response time during the final phase is relatively short. A thruster system may subsequently be added to an ASBM, such as the DF-21D, to increase its terminal speed and maneuverability so that it will not be easily intercepted by ground defenses.
Additionally, even if the People's Liberation Army's (PLA) new ASBM has a smart warhead design, it will not be able to "see" its target during the reentry phase due to ionization blockage. Only once it slows down in the lower atmosphere can it start searching for its target, which is not too different from an air-breathing platform at this stage.
Therefore, a final speed of more than Mach 2 for the DF-21D's warhead is the maximum. This allows the ASBM enough time to acquire its target and avoid being intercepted.
If the incoming DF-21D is detected at an altitude of 80 km, assuming a reentry speed of Mach 10 and a subsequently reduced speed of Mach 2 at a 5-km altitude, at least 30 seconds will have passed before impact. During this time, an aircraft carrier sailing at 25 knots will have traveled at least 375 meters.
A Nimitz-class carrier’s dimensions are 330 m by 80 m. That means that even if China’s reconnaissance assets were able to determine the exact location of a U.S. carrier, the vessel will have sailed outside of the designated impact area.
Moreover, this is considering that the DF-21D has an accuracy of 10 m circular error of probability (CEP).
A conventional ballistic missile (short-range or medium-range) hitting a stationary target is a difficult task. Considering the evasive maneuvers American surface combatants would be taking, it would be even more difficult for China’s ASBM to score a direct hit.
This back-of-the-envelope calculation assumes a U.S. fleet receives no real-time intelligence from its satellite constellation, designed specifically to detect missiles and calculate their trajectories. This scenario also assumes the fleet has no anti-ballistic missile capabilities, such as SM-3 missiles. These are, of course, part of a worst-case scenario, which is not likely.
Additionally, the DF-21D’s reliance on its onboard sensors for target acquisition will not be sufficient. Employing other scout platforms, such as helicopters or submarines tagging the U.S. fleet, to illuminate the target will increase the missile's accuracy and lessen the weight of its payload.
However, getting the scout into an aircraft carrier battle group's visual range without being detected by its vast array of sensors already on high alert would be difficult. Therefore, the success of the ASBM depends on the following factors:
- Target acquisition capabilities onboard the DF-21D or scout platforms.
- Terminal phase maneuverability with high response thrusters that can create side forces.
- Altitude control and steering capabilities.
Since the DF-21D’s terminal speed is not very high, guidance control is not a big problem. Nevertheless, slower speeds also make it easier to for the U.S. Navy's area defense assets to intercept it.
The PLA may have to add a booster to increase the final speed and make it an effective ASBM. With all these design factors, a 500-kg warhead design may have room to carry only about 150-200 kg of conventional high explosives, which may not be enough to sink a carrier at Mach 2+ speed, though substantial damage would be certain.
China’s first strike will be deemed as hostile and could lead to an all-out war. Their ASBMs are on mobile launchers and can be very difficult to pinpoint and neutralize, though the U.S. does have a database for China’s hard and soft targets (Taiwan’s may not be as extensive).
The U.S. Navy’s aerial strike intensity is tremendous, but its aircraft carriers will have to sail within the strike range of F/A-18 and F-35C fighter jets. This poses a dilemma for U.S. commanders because that would put their fleet within the range of China's ASBMs.
Additionally, China’s A2/AD capabilities will compel U.S. military planners to fine-tune their war plans to prepare for a contingency. Despite all these facts, it is always safe to assume that Chinese technical capabilities are more advanced than is often believed — as in the case of the PLA’s anti-satellite (ASAT) capabilities, which surprised the West in 2007.
Though the DF-21D’s ability to sink an aircraft carrier may be doubtful, it is nevertheless a good deterrence weapon, as American commanders may not be willing to take the risk. The issue is whether Chinese Communist Party General Secretary Xi Jinping (習近平) is ready to start a war with the U.S.
Holmes Liao is a senior advisor at Taiwan's Institute for Information Industry.