The debate on the virtues and evils of deploying a national ballistic missile defence system has been going on for decades. Ever since the 1960s there have been a number of US proposals for ballistic missile defence systems, including the Nike-X (1964), Sentinel (1967), Safeguard (1969), Strategic Defence Initiative (1983), Brilliant Pebbles (1990), the Global Protection Against Limited Strikes (GPALS, in 1992, under G.H.W Bush) and the Patriot (PAC III in 1991).

The development and deployment of the proposed NMD system gained strength after the Rumsfeld Commission Report (1998), which identified the threat of a limited strategic ballistic missile attack by rogue states (North Korea, Iran etc.) on the United States. Also, the need for a NMD was felt, to defend the US from small accidental or unauthorized launch of strategic ballistic missiles from other nuclear capable states like China and Russia.

Despite the apparent need for defence against possible attacks, the downside of the proposed development and deployment of a National Missile Defence system far outweigh its upside. The arguments against the NMD focus on its technological drawbacks, high cost of development, scepticism about the system's performance and its uncertain architecture, the ease of circumventing it and the impact it would have on the strategic relationship with China and Russia, not to mention its adverse impacts on the NPT and MTCR.

The continued pursuance of a NMD system will also destabilize "arms race stability" and "crisis stability" as argued by McNamara during the Cold War period. From the NPT's standpoint, deployment of a NMD system undermines the treaty's unequivocal long term objective of elimination of nuclear weapons by the five Nuclear Weapon States, since it will trigger an arms race, with both China and Russia trying to create countermeasures and more sophisticated weapons to defeat the NMD, accelerating vertical proliferation.

Sharing missile defence technology means exporting missile technology, which would stimulate missile proliferation by Russia and China, and encourage them to share this technology with nations that the US categorizes as "rogue states", thus defeating the very purposes of the NPT and the MTCR.

Besides, there are a number of technical limitations to the development of the NMD. This was evident in the report of Gen (retd) Larry D Welch, USAF, (1998) that came to be known as the "Rush to Failure" report. It characterized the NMD system as relying too little on testing and too much on unrealistic simulation, despite a very low success rate of actual "hit to kill" intercepts. Given the technology gap, there is also the question of costs associated with developing the NMD system, running into tens of billions of dollars, if not into hundreds, with no guarantee that the system will work.

Further, even if the US manages to solve the technological hurdle of testing the system's efficiency by improving these "hit to kills" ratios, there is no basis for adjudging the ability of highly complex systems to perform under battlefield conditions, facing potential well developed countermeasures and a determined adversary. Also, since perceived potential threats cannot be enumerated, there is no way to agree on the performance level of a proposed NMD system that would protect the US; thus, bringing into question the required system architecture for the proposed NMD system. Given the cost, complexity and comparative ease of intercepting a long range ballistic missile, it is highly unlikely that a rogue state will use this means of delivering weapons of mass destruction. Other alternatives like "suitcase bombs" seem more likely.

Even if we assume that rogue states will have the technological expertise to deliver weapons of mass destruction via long range ballistic missiles; it seems likely that it will also have developed measures to counter a NMD system. Lastly, deployment of a NMD system will jeopardize the strategic relations between the US with China and Russia. It will have serious repercussions on the nuclear posture of these nations, thus leading from an era of post cold war "cold peace" to an era of "cold conflict".

It is difficult to accept the viability of the proposed NMD system, since it seems to be an ill-conceived response to an undefined and uncertain threat. In the long run, the deployment of NMD systems will, in all probability, lead to a highly volatile security environment, diminishing US security, not enhancing it. The wise response would be to adopt an arms control perspective and ban the development of missile defences, leading to a cost effective solution to secure a safer global environment.