It also incorporates a manoeuvrable warhead to help find its target. Such a device would be instrumental in striking a vessel in the open ocean or denying access to a potential opponent in transiting to a conflict zone. An August 2011 report by Taiwan’s Ministry of National Defense declared: ‘A small quantity of the missiles [was] produced and deployed in 2010, increasing the difficulty of military manoeuvres in the region for the US Army’.

While China’s naval forces have grown substantially over the past decade, they are — as yet — no match for US forces in open combat. But investment in ASBM technology is now levelling the playing field, giving China a true ‘anti-access/access denial’ weapon. And there is certainly no disputing the potential of such a weapon. Dr Andrew Erickson, of the US Naval War College, described the new missile system as placing US forces ‘on the wrong side of physics’ at a recent lecture. If the US could not credibly defend against such a weapon, its carriers and capital ships would need to stay out of range. Losing the ability to launch carrier strikes in a possible theatre of conflict would be a devastating blow to US forces in the region.

This said, the theoretical range of the DF-21D is debatable. Chen Bingde, chief of the People’s Liberation Army (PLA) General Staff remarked the weapon had a range of 2,700 km in July 2011 — an almost 80 per cent increase in the theoretical range that most US assessments consider accurate. Such an increase in range would push the safety zone of US surface vessels out to the vicinity of Guam. This analysis is at odds with the 24 August 2011 US Department of Defense (DOD) analysis of China’s military capabilities. The report quotes the range of the DF-21D as ‘exceeding 1,500 kms’, which is in line with previous US estimates. With Chen’s comment coming one month before the release of the new report, one would assume DOD planners would have had the necessary time to make any changes if they felt this information accurate.

An important question bears asking: whose estimate is correct? While we may never obtain a certain answer, it is clear that the weapon system’s range is of critical importance. A large part of the US Navy’s operational capacity to attack and defeat a land- or sea-based target is based on the strength of its carrier battle group. US carriers have previously been able to attack and strike at will with little fear of reprisal. Thus, with the range of China’s ASBM system now possibly much greater than previous estimates, protective measures become of great importance. US forces are rumoured to have some defensive capability in the AEGIS Standard Missile-3 (SM-3) ballistic missile defence system. But even still, they could quickly find themselves in a tactical bind. If China fires large numbers of ASBMs at US vessels which then exhaust their stores of SM-3s before ever reaching a conflict zone, US forces will either have to continue transit without any defences or return to port. For this reason, it is crucial that US forces know where they might operate uninhibited by Chinese ASBMs.

US strategists must also make tactical judgments based only on intelligence and second hand reports. The PLA has tested components of the missile system and may have done various land-based tests but has never tested the DF-21D in the open ocean against a moving target. This denies US planners the capability to make much more accurate predictions about the range and operational capabilities of the system.

Chinese military planners, without even fully testing the ASBM system, have placed US forces in a challenging position. Even if General Chen’s statement was an exaggeration or a theoretical range, this debate demonstrates the difficulties US strategists face in dealing with this new weapon. And now with the possibility of a larger range, US planners will need to ponder long and hard if and how they might use surface combatants in the Pacific Ocean during a conflict.

Harry Kazianis is a deputy editor for e-IR and a policy analyst at the Foreword Group.