The United States is on the verge of deploying a national missile defense system intended to shoot down long-range missiles. The Clinton administration is scheduled to decide this fall whether to give the green light to a system that is expected to cost more than $60 billion, sour relations with Russia and China, and block deep cuts in nuclear arsenals.
But the real scandal is that the defense being developed won't work - and few in Washington seem to know or care.
The chief difficulty in trying to develop missile defenses is not getting vast systems of complex hardware to work as intended - although that is a daunting task. The key problem is that the defense has to work against an enemy who is trying to foil the system. what's worse, the attacker can do so with technology much simpler than the technology needed for the defense system. This inherent asymmetry means the attacker has the advantage despite the technological edge the United States has over a potential attacker such as North Korea.
We recently completed, along with nine other scientists, a yearlong study that examined in detail what countermeasures an emerging missile state could take to defeat the missile defense system the United States is planning. That study shows that effective countermeasures require technology much less sophisticated than is needed to build a long-range missile in the first place - technology that would be available to the potential attacker. This kind of analysis is possible since the United States has already selected the interceptor and sensor technologies its defense system would use. We assessed the full missile defense system the United States is planning - not just the first phase planned for 2005 - and assumed only that it is constrained by the laws of physics.
We examined three countermeasures in detail, each of which would defeat the planned US defense.
A country that decided to deliver biological weapons by ballistic missile could divide the lethal agent into 100 or more small bombs, known as ''bomblets,'' as a way of dispersing the agent over the target. This would also overwhelm the defense, which couldn't shoot at so many warheads.
The Rumsfeld panel, a high-level commission convened by Congress in 1998 to assess the ballistic missile threat to the United States, noted that potential attackers could build such bomblets. We show this in detail.
An attacker launching missiles with nuclear weapons would have other options. It could disguise the warhead by enclosing it in an aluminum-coated Mylar balloon and releasing it with a large number of empty balloons. None of the missile defense sensors could tell which balloon held the warhead, and again the defense could not shoot at all of them.
Alternately, we showed that the warhead could be enclosed in a thin shroud cooled with liquid nitrogen - a common laboratory material - so it would be invisible to the heat-seeking interceptors the defense will use.
These are only three of many possible countermeasures. And none of these ideas is new; most are as old as ballistic missiles themselves.
How is it possible that this problem is being ignored? The Pentagon, saying it must walk before it can run, has divided the missile defense problem into two parts: getting the system to work against missiles without realistic countermeasures and then hoping to get it to work against missiles with countermeasures. Few doubt the first step could eventually be done, but such ''walking'' would be useless against an actual attack by North Korea or any other country.
The second step - getting the defense to work against countermeasures - is the one that matters. And our study showed in detail that the planned defense won't be able to do this.
Unfortunately, the debate in Washington revolves around only the first step. The Pentagon plans to determine the ''technological readiness'' of the system this summer after three tests that lack realistic countermeasures. And President Clinton's decision whether to deploy will be based on that assessment. The deployment decision is simply being made on the wrong criteria.
This situation is similar to a group of people deciding to build a bridge to the moon. Instead of assessing the feasibility of the full project before moving forward, they decide to start building the onramps, since that's the part they know how to do.
The reality is that any country that is capable of building a long-range missile and has the motivation to launch it against the United States would also have the capability and motivation to build effective countermeasures to the planned defense. To assume otherwise is to base defense planning on wishful thinking.
David Wright is a researcher at the Union of Concerned Scientists and the MIT Security Program. Theodore Postol is professor of science, technology, and national security at MIT. Both are physicists.
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