Long before the 9/11 terrorist attacks, strategic thinkers and leading think tanks in the US had started anticipating new transnational security threats to international peace and security. The conventional mechanism of nuclear deterrence was no longer valid because of the multiplicity of dangers ranging from civil wars and ‘rogue’ governments to the secret proliferation of weapons of mass destruction. In fighting non-state actors, nuclear retaliations can hardly be relied upon due to their ability to move from one country to another within a few hours and their willingness to accept even their own destruction as a consequence of their actions. US strategic planners sought to respond to the evolving threat environment by developing credible non-nuclear capability with the potential to strike distant targets around the globe in a short period of time. Soon this idea gained currency among policymaking circles and, after 9/11, the US Department of Defence formally started work on developing Conventional Prompt Global Strike (CPGS) capability.The goal of this concept was to give the US military the ability to acquire “high-precision conventional weapons” capable of striking “fleeting targets” anywhere in the world in an hour or less. Another major incentive toward developing CPGS capability was to be in a position to pre-empt an attack on US soil by destroying the means of attack without resorting to nuclear weapons. CPGS capability is believed to allow for reduction in nuclear force levels and also defeat the efforts of potential proliferators. In 2006, the Bush administration announced its intention to equip trident missiles deployed on nuclear submarines with conventional rather than nuclear warheads. CPGS weapons, if successful, can destroy any target from missile bases to production facilities for weapons of mass destruction (WMD) within a few minutes.Another scenario invoked for the use of CPGS weapons is targeting terrorist groups’ gatherings and hideouts. However, because of warhead ambiguity and other technical hindrances, US Congress opposed this plan. Since then, the Pentagon is thinking about developing other technically sophisticated non-ballistic systems. Owing to the huge investment the CPGS project entails, the plan is unlikely to become operational before 2025. Some advocates of the project have argued that CPGS weapons could be used to interdict the illegal transfer of nuclear materials from rogue states to terrorists. CPGS weapons can be used to counter sophisticated defensive capabilities, deny irresponsible governments the ability to employ their nuclear warheads and kill high value terrorists.Nevertheless, concerns remain over the feasibility of prompt global strike. Most troubling is the possibility that its use could increase the probability of an accident involving strategic nuclear forces. The inability of radars and early warning systems to distinguish between a CPGS weapon and nuclear warhead can lead to serious misunderstandings with potentially disastrous consequences. The short flight time of ballistic missiles also leaves little time for an assessment of the situation.Some Russian analysts are of the view that the principle argument advanced by the US authorities in favour of their allegations that Iran is acquiring nuclear capability is the development of long-range ballistic missiles by Iranian nuclear scientists. It is well known that long-range missiles are extremely expensive and technologically demanding because they have to leave and re-enter the earth’s atmosphere during their flight path. It is therefore not a rational strategy to use a ballistic missile to strike a target with a relatively limited effect. Thus, US experts conclude that Iran is developing long-range capabilities in order to be fitted with a nuclear weapon. However, the Pentagon’s efforts to downgrade intercontinental nuclear weapons with conventional warheads stands in direct logical contradiction to its own arguments against Iran. If the US can use long-range missiles for conventional weapons, Iranian long-range missiles cannot be taken as an indicator of Iran’s nuclear ambitions.If a trident missile is launched to attack an underground WMD laboratory in Iran, it could immediately be recognised by the early-warning systems of Russia or China, much like the launch of an atomic weapon. In such a scenario, the governments of Russia and China would have less than 10 minutes to decide on the appropriate reaction to the real or supposed nuclear attack. An unfortunate chain of events could lead to an order being issued for a nuclear counter-strike before the actual target of the CPGS weapon is determined. Pentagon officials consider that secure emergency communication lines can be used to clear up any such kind of misunderstanding. However, it is also true that, in times of crises, the country planning to launch missile attacks will not be very truthful about its intentions. In 1995, a nuclear war was barely avoided when Russia’s early warning satellites detected a US research rocket shot from a Norwegian island, triggering an alarm at the highest level in Moscow.Other optimal weapons for the realisation of the CPGS plan are cruise missile, stealth aircraft, and B1 and B2 bombers, but the US air force is not in a position to maintain a worldwide network of airbases in order to reach possible targets expeditiously. Other questions about the ability of intelligence-gathering networks to provide adequate support as well as the capacity of existing intercontinental delivery systems also increase apprehensions. The pressing requirement for locating underground weapons laboratories or missile launching pads is a foolproof method of gathering and judging intelligence, which is perhaps impossible in most cases. Many critics of CPGS have also raised the possibility that the US initiative of developing conventionally armed long-range ballistic missiles will be followed by similar initiatives in other countries. Thus CPGS could lead to a new type of arms race. Despite continuing joint efforts by the US and Russia to limit strategic nuclear warheads, technological advances such as CPGS have strengthened the arguments of different lobbies in Moscow that oppose any reductions in nuclear arsenals. The writer is a research scholar and a former visiting fellow at the Monterey Institute of International Studies, California. He can be reached at rizwanasghar7@hotmail.com