Why aren’t self-interrupting nuclear weapons a thing?

The current global nuclear military doctrine is based on a cat-and-mouse game in which the outcome could well be the destruction of the human race. It revolves around the assumption that any belligerent use of nuclear weapons against a single nuclear-weapon country, however limited, could result in all-out thermonuclear war.

This premise is based on the doctrine of Mutually Assured Destruction (MAD), a strategic concept that ensures that any initial nuclear attack would provoke a devastating retaliatory response, leading to the mutual destruction of all involved.

MAD has been the cornerstone of nuclear deterrence, first brought to prominence in the 1950s by Henry Kissinger, the former US Secretary of State, and later coined by military analyst Donald Brennan in the 1960s. Today, the specter of this doctrine looms as ominously as it did during the Cold War, underscoring the fragility of modern peace.

But why? As John R. Allen and Peter Levin explain in a thoughtful piece in IEEE spectrumThe main reason is that once the most powerful human weapons are unleashed, there is currently no way to stop them. This is by design and perhaps one of the best deterrents to launching them in the first place.

After all, accidents can happen have happened in the past. However, some military thinkers believe it is time to reconsider this policy. So is it possible to add self-destruction or abortion functions to nuclear weapons?

Let’s find out.

I have become death, the destroyer of worlds

In the aftermath of the first and only deployment of nuclear weapons at the end of World War II, only a select few countries possessed them, the United States and the Soviet Union.

The United Kingdom and France soon joined the ranks in the 1950s. The figure has grown since thenwith as many as eight (perhaps nine) countries in possession of these highly destructive weapons of war.

Some of them, such as Russia, North Korea and China, are likely on a collision course that could escalate into the unthinkable: nuclear conflict. Russia, for example, has also made it abundantly clear that it is seriously considering limiting nuclear use in Ukraine.

The country has even changed its legislation nuclear doctrine rules in light of Western support for Ukraine. While this move was most likely intended to draw a line in the sand, it has done little to allay the already heightened fears among those concerned about the possibility of nuclear Armageddon.

And the threat is very real. If the unthinkable happens, it will only be a matter of minutes before hundreds, if not thousands, of nuclear warheads are launched.

Can nuclear weapons be disabled in flight?

Modern long-distance delivery platforms, such as intercontinental ballistic missiles (ICBMs) or their maritime equivalents, can each carry multiple nuclear warheads. Just a few of these are enough to completely erase a city from the map.

You may be surprised to learn that each of these ICBMs is irreversible upon release. Once they leave their launch vehicles, there is no way to recall, deactivate or abort them.

This deliberate design policy was chosen due to concerns about electronic tampering. For example, enemy radio signals can disable the weapons once they are in the air. In other words, the design prevents electronic warfare systems from disarming incoming nuclear charges.

The bottom line is that policymakers deliberately avoid this possibility. The irony, however, is that most systems have fail-disable systems installed during the testing phase. These systems are regularly tested and activated when the missile performs outside expected parameters.

A Minuteman III rocket did just that last November. During a routine nighttime test launch, that particular LGM-30G test vehicle ended up “safely” over the Pacific Ocean.

Such systems usually consist of explosives attached to the airframe that can be activated remotely to dramatically ‘abort’ a launch. Such mechanisms, technically called flight termination systems (FTS), provide militaries with the ability to disable or destroy launch vehicles in flight.

These systems usually have independent power sources, which provides important redundancy. Other types of rockets, such as liquid-fueled rockets, also have options to jettison fuel to abort rocket flights.

Other munitions, such as anti-aircraft guns, tracer munitions and torpedoes, also have a more rudimentary ‘self-destruct’ failsafe. These are designed to render ammunition inert in the all-too-common chance of them missing their targets.

Paper-thin international agreements

Despite the deliberate design, international agreements exist to prevent a large-scale nuclear exchange. For example the Accident Agreement from 1971a treaty between the US and the Soviet Union, established a protocol to reduce the nuclear threat and implement a policy of restraint. Yet it is not entirely reassuring.

“In the event of an accident, the Party whose nuclear weapon is involved shall immediately make every effort to take the necessary measures to neutralize or destroy such weapon without causing damage,” it said. How this is to be achieved is left to the interpretation of the signatories.

Although the technology exists, as we have already emphasized, it is not standard practice to incorporate it into operational nuclear weapons. For example, carrying bidirectional communications for telemetry and guidance is common in civilian missiles and other military systems.

In the case of such high-stakes launches as nuclear weapons, it would not take much effort to include even monodirectional links that provide some insurance against accidental launches.

Countdown to destruction

In all cases, speed is the key word. The United States’ current Minuteman III nuclear missiles could reach Russia in about 30 minutes. This consists of a boost phase of approximately 5 minutes, during which the launch vehicle delivers the nuclear payload from each rocket into the Earth’s atmosphere.

Then the rocket’s engine is turned off and the launch vehicle travels in a parabolic arc for another 20 minutes. Once close to the target, the warheads return to Earth in the reentry phase and on their path to the final destination.

Interception could occur in any of the different key windows. The first is the boost phase, as mentioned above. At this point, remote controls should be able to easily contact the rocket through various ground, sea, or even space-based transmitters.

Abort instructions can also be easily sent during the longer parabolic slide phase. However, problems arise when they are dispatched near the end of the weapon’s mission, the reentry phase.

When the reentry vehicle with the warhead enters the atmosphere, it is enveloped in a plasma envelope. This plasma interferes with the reception of radio waves. Therefore, during the return and descent phases, which last about a minute, it is only possible to send abort instructions once the plasma has disappeared.

In practical terms, there is a very small window of communication, lasting only a few seconds before detonating. Moreover, this communication would probably only be possible with transmitters in space.

Abort, abort, abort!

As worrying as that sounds, existing technologies could also be used to contact nuclear warheads in this last critical time frame. For example, Allen and Levin explain this in space Global Positioning Systems (GPS) use L-band radio signals that can be transmitted at approximately 50 bits per second.

L-band can penetrate clouds, fog, rain, storms and even vegetation, proving to be an ideal option. Satellite communications systems compensate for weather, terrain and urban canyons using specialized systems K-band beamforming antennas and adaptive noise-resistant modulation techniques, such as spread spectrum, where data rates are measured in megabits per second (Mb/s).

For each type of signal, the received carrier strength would be approximately 100 decibels per milliwatt. Any value above this level, likely at or near the rocket’s apogee, would increase reliability without compromising safety.

Other assistive technologies are also available to receive and amplify low-power signals, filter out interference and noise, and even encode messages for transmission and reception over long distances. Military systems are very advanced in using cryptography to encrypt messages and signals.

Artificial intelligence and quantum computers could further find a welcome home on this front. With the development of self-landing missiles (such as those developed by SpaceX), it could also be feasible to have nuclear weapons recalled upon request.

For applications such as nuclear weapons, there is no real reason why signals, codes and disabling protocols cannot be dynamically programmed before launch. This would dramatically increase security and reduce the possibility of ‘hacking’ by the enemy.

Will we ever see self-destructive nuclear weapons in the future? We have the means, but what is needed is the will.