ElectroMagnetic Pulse (EMP) bombs can destroy power grids and electronics. Why are experts so worried about an EMP attack?
EMP attack threat background
While testing high altitude nuclear weapons in the 1960’s, scientists noticed something startling: one of their explosions had crippled telephone lines and scrambled electronics hundreds of miles away.
The scientists had expected an electromagnetic pulse (EMP) from their tests, but they had no idea it would be so powerful. Since then various countries – and even terrorists– have been rumored to be developing powerful EMP weapons. Since they could be used for a surprise attack, the weapons are shrouded secrecy, and no country has actually admitted to having one.
To be clear, EMP attacks are different from solar flares from the Sun, which can also produce a debilitating EMP pulse at a different wavelength.
How an EMP weapon works
When a large atomic bomb goes off at a high altitude, photons and high energy electrons from the blast interact with the Earth’s magnetic field. Next, a fast, powerful EMP wave spreads outward and envelops power lines, antennas, transformers and and electronic devices.
While the precise effects are difficult to predict, many experts think a large EMP attack could spread across an entire continent, destroying key civilian and military electrical and communication systems.
An EMP wave does not kill humans – it destroys their electrical and electronic infrastructure instead.
Compared to traditional warfare strategies, an EMP attack could provide an attacker with several compelling advantages, including:
- Surprise: used without warning, an attack could take down many systems instantly
- Asymmetry: weak actors could devastate much larger rivals with a single device
- Cost: compared to fielding traditional weapons and nuclear arsenals, the cost of an EMP device would be very small
- Coverage: large devices can cover an entire continent
- Deniability: like cyber attacks, a clever an attacker might be able to hide their role in an attack
The effects of an EMP attack
No one really knows what a large EMP attack would do to the U.S., but many speculate about it. In a 2016 presidential debate, Senator Ted Cruz frightened listeners by painting a nightmarish scenario in which North Korea uses a satellite to direct an EMP attack over America.
Some expect that a large EMP weapon could blanket the entire United States, according to expert testimony to a Homeland Security committee. Such an attack could knock out power grids, communication networks, financial systems, healthcare facilities, transport networks and water systems.
Perhaps the most alarming prediction came during testimony given at an EMP commission hearing in 2008, when experts predicted that within 12 months of a major EMP attack, up to 90 percent of the U.S. population could perish.
Some have even speculated that the loss of power at U.S. nuclear plants for a long duration could trigger meltdowns at nuclear power plants.
In addition, military mobilization capability might also be compromised, according to a 2004 report (pdf) from a special commission set up to examine EMP threats.
Favorite theorist topic
When considering dire predictions, it is useful to remember that the actual effects of an EMP device are difficult to predict, and that some of the most alarmist EMP predictions may be exaggerated.
The EMP attack topic is a favorite among politicians, survivalists and ex-security officials, who may sometimes be prone to exaggeration.
Defending against an attack
From a personal perspective there’s little that an individual can do to defend against an electromagnet wave.
From a federal perspective, U.S. officials are working on plans to stockpile spare transformers for large power plants, so they could be replaced quickly after an attack. Such transformers usually take years to make.