For almost a century now, governments and their military forces have enlisted the aid of scientists and engineers to invent weapons, devise defenses, and advise on their use and deployment.

Theodore “Ted” Postol has long been a critic of fantastical defense technologies. He still is. Visual: MIT

Unfortunately, scientific and technological realities don’t always conform to the preferred policies of politicians and generals. Back in the 1950s, some U.S. officials liked to proclaim that scientists should be “on tap, not on top”: in other words, ready to provide handy advice when needed, but not offering advice that contradicted the official line. That attitude has persisted into the present, but scientists have steadfastly refused to play along.

One of the best-known leaders of this resistance is Theodore “Ted” Postol, professor emeritus of science, technology, and national security policy at MIT. Trained as a physicist and nuclear engineer, Postol has spent a career immersed in the details of military and defense technology. He worked for Congress in the now-defunct Office of Technology Assessment, then in the Pentagon as an adviser to the Chief of Naval Operations before joining academia, first at Stanford University and then returning to his alma mater, MIT.

Throughout, he has been an outspoken critic of unworkable concepts, impractical ideas, and failed technological fantasies, including Ronald Reagan’s “Star Wars” system, the vaunted Patriot missile of the first Gulf War, and more recent intercontinental ballistic missile defense concepts tested by the U.S. His investigations and analyses have repeatedly revealed self-deception, misrepresentation, flawed research, and outright fraud from the Pentagon, academic and private laboratories, and Congress.

When we contacted him, we found that, far from being retired at age 70, he was preparing to travel to Germany to consult with the German Foreign Ministry on European-Russian relations. His work exemplifies the eternal verity that if something sounds too good to be true, it usually is. In the exchange below, his responses have been edited for length and clarity.

Undark — The U.S. has been striving for some kind of defense against ballistic missiles ever since Sputnik in 1957. As a critic of the concept, can you explain why a truly effective defense against incoming missiles isn’t really technologically possible?

Ted Postol — In the case of missile defenses of the type the United States is building, all the objects that would be seen by the interceptors would appear like points of light. Unless the interceptor has prior knowledge, like some points of light having a well-defined brightness relative to others, it has absolutely no way of determining what it is looking at and as a result, what to home in on.

A common misconception is that, were such countermeasures to succeed, warheads and decoys must look alike. All that is required is that all the objects look different and that there is no knowledge of what to expect. As a result, an enemy can modify the shape of the warhead (for example by inflating a balloon around it) and completely alter its appearance to a distance sensor. If an enemy is capable of building ICBMs and nuclear warheads, the enemy certainly has the technology to build and deploy balloons, as well as to do simple things to modify the appearance of warheads. The technology to implement such countermeasures is very modest while the technology to defeat it basically does not exist — there is no science that can be utilized by the engineers that will allow the defense to determine what it is seeing.

So my objection to the high-altitude missile defenses that are being deployed by the United States is very simple — they have no chance of working against any adversary who has even a modest understanding of what they are doing.

UD — What’s the current status of the NATO theater system? Obama cancelled one project initiated by President George W. Bush, but do you think it’s likely to be more vigorously pursued by the new administration in Washington?

TP — The current NATO theater missile defense is alive and well. This missile defense is built around a modified surface-to-air-missile known as the Standard Missile-3 (SM-3). The original concept was to launch interceptors from Aegis cruisers and use the Aegis radars to detect missiles and warheads and to guide the interceptors. However, it turns out that the Aegis radars could not detect and track ballistic missile targets at long enough range to allow time for the interceptor to fly out and engage a target.

A good question to ask is how could the U.S. have possibly chosen to develop and deploy such a system and not known that this was the case. One explanation is that the choice of the missile defense was dictated purely by political imperatives and as such, nobody involved in the decision-making process did any analysis, or cared to determine whether or not the concept made any sense. If you find this to be scandalous, I completely agree.

The political problem with the Aegis-based missile defense is that the number of interceptors that could potentially to be deployed by the United States will grow very large by 2030 to 2040. It could in theory reach beyond the center of the continental United States and make intercepts of incoming warheads that have been tracked by U.S. early warning radars.

This creates the appearance that the United States could potentially defend the continental United States against many hundreds of Chinese or Russian warheads. It is a basic barrier to future arms reductions because the Russians are unwilling to reduce the size of their forces to levels where they might at some point be susceptible to vast numbers of U.S. antimissile interceptors.

The reality is that the defense system will have little or no capability. The early warning radars have no ability to discriminate between warheads and decoys (these particular radars are a very low resolution) and the SM-3 interceptors would not be able to know which of many targets it might encounter is the warhead. Nevertheless, the appearance that the United States is striving to have the ability to defend itself with hundreds of interceptors will raise profound and highly problematic barriers to future attempts at arms reductions.

The United States has a substantial capability to destroy large parts of Russian forces in a first strike. Although such an action would almost certainly be suicide, military planners on both sides (Russian and American) have taken this possibility quite seriously throughout the decades of the Cold War. It is very clear from statements made by Vladimir Putin that he does not reject the possibility that the United States would try to disarm Russia in nuclear strikes. Hence, even though neither side has any realistic chance of escaping an existential catastrophe if weapons are used in this way, the possibility is taken seriously and influences political behavior.

UD — In 1995, a Norwegian research rocket almost started World War III when the Russians initially thought it was a U.S. attack. Your analysis pointed out how the incident revealed glaring flaws in Russian warning and defense systems. Have there been any improvements in Russia’s early warning capabilities?

TP — The Russians are involved in a highly-prioritized effort to build a more capable early warning system against the U.S. surprise attack. The system they are building is based on the use of ground-based radars of different designs that have overlapping search fans and different engineering technologies. It is clear that this is part of a strategy to minimize the chances of a common mode false alert while also trying to provide significant redundancy to guarantee warning of an attack.

Only recently, within the last year, have the Russians finally been able to obtain 360-degree radar coverage against ballistic missile nuclear attack. When one looks at their literature on early warning systems, it is very clear from their statements that this has been a goal they have been trying to achieve for many decades — starting from the time of the Soviet Union.

The Russians also appear to be employing a new class of over-the-horizon-radars that appear to me to have nothing to do with air defense, as stated in the Russian literature. If one looks at the location and characteristics of these over-the-horizon radars, it is very clear that they are aimed at providing warning of a ballistic missile attack from the North Atlantic and Gulf of Alaska.

The problem is that these radars are extremely easy to jam and cannot be depended on to be highly reliable in a hostile environment. All of the indications today unambiguously indicate that the Russians still do not have the technology to build a global space-based infrared early warning system. They do have some limited capability to build systems that look at very small areas of the earth’s surface, but nothing close to global coverage.

UD — What are the dangers that a small nuclear power with limited missile capabilities such as North Korea could cripple the world’s satellite communications with a directed electromagnetic pulse nuclear detonation, even over their own territory? Is there any defense against such an attack?

TP — Significant damage could be done to low-altitude satellites, some immediately and others at later times. However, a single low-yield nuclear explosion would not necessarily destroy all communications.

My own personal judgment is that the biggest danger from North Korea is that they could stumble into a nuclear confrontation with the West. North Korean leadership is not crazy. It is instead a leadership that believes that it should look unpredictable and aggressive in order to keep South Korea and the United States off-balance as part of an overall strategy to avert military action by the South and U.S.

As a result, the North Koreans intentionally do things that create the appearance of recklessness — which is in fact a reckless strategy by itself. The greatest danger is that they will inadvertently step over a line and precipitate a military response from the West or from the South. Once this gets going no one can know where or how it will end. Probably the only near certain outcome is that North Korea will be destroyed and cease to exist as a nation. However, no one can predict that nuclear weapons will not be used, and the reaction of China to having U.S. and South Korean troops directly at its borders could have unpredictable consequences.

So North Korea is definitely a very dangerous situation.

UD — Many people, including prominent former members of the defense establishment such as Henry Kissinger, William Perry, and Sam Nunn, are calling for the total elimination of nuclear weapons from the Earth. Do you think this is a reasonable and attainable goal?

TP — I am an enthusiastic supporter of the “vision” of the world free of nuclear weapons.

I personally think it will be very difficult to have a world free of nuclear weapons unless the global political situation is entirely transformed from what it is today. However, this is not a criticism of the visionary goals set by Shultz, Perry, Nunn and Kissinger.

At the moment, the United States and Russia are behaving in ways that indicate that neither side is ready to take steps towards that vision. My own view, which is quite unpopular in this current political environment, is that the United States is the country in the driver’s seat with regard to this issue.

The United States is in the process of building a vast nuclear arsenal that appears to be aimed at having the ability to fight and win nuclear wars. The fact that the concept of fighting and winning a nuclear war is completely divorced from the realities of nuclear weapons effects has not deterred the United States from moving forward as if such an objective is possible.

Given this behavior, it is to be expected that the Russians would be scared to death, and that the Chinese would also be close behind them. I believe the situation is extremely dangerous and in fact getting more so.

Mark Wolverton, a 2016-17 Knight Science Journalism Fellow at MIT, is a science writer, author, and playwright whose articles have appeared in Wired, Scientific American, Popular Science, Air & Space Smithsonian, and American Heritage, among other publications. His most recent book is “A Life in Twilight: The Final Years of J. Robert Oppenheimer.”