EMP Threat to National Security

Recently the threat of an electromagnetic pulse (EMP) nuclear attack on the U.S. has been getting considerable attention -- especially for a "non-traditional" threat. Typically discussions of nuclear attacks focus on the surreptitious introduction of a nuclear weapon -- or crude radiological weapons (aka "dirty bomb") -- into the United States. Talking about EMP was quite out of favor -- the sort of thing that old "Cold Warriors" talked about while lamenting the glory days of a "worthy" Soviet adversary. But this seems to be changing.

On April 26, Investor's Business Daily ran an editorial titled "Shock and Awe" about the danger to the US of an EMP-causing nuclear attack. (I discovered this article on Factiva, and, sadly, cannot link to it.) The attack would come from a nuclear armed missile fired from a small ship in the waters off the US coast. IBD doesn't mince words: they say it would be the end of our economy.

Nobody is harmed or killed immediately by the blast. But life in the U.S., the world's only superpower and its largest economy, comes to a screeching halt as a country dependent on cutting-edge 21st century technology regresses in time almost a century instantaneously.

IBD goes on to line up the potential adversaries that are testing or have missile technology that could enable such an attack: China's ballistic missile-carrying sub, North Korea's nuclear and missile technology, and recent Iranian tests of missiles intended to detonate in mid-air.

Iran has surprised intelligence analysts by describing the midflight detonations of missiles fired from ships on the Caspian Sea as "successful." Imagine one of those missiles carrying an Iranian nuke being fired from a ship in international waters off the American coast, detonating high over an Iowa cornfield.

If that's not scary enough, IBD says al Qaida could do the same thing with some merchant ships and a $100,000 black market SCUD. A little googling turned up this WSJ article titled "The Mother of All Blackouts," posted on Free Republic. This article sounds like the source of the IBD piece. Both lament that the EMP threat gets little attention compared with the 9-11 Commission's report. Apparently the Commission to Assess the Threat to the U.S. from Electromagnetic Pulse (EMP) Attack made its report the same week as the 9-11 Commission. Now what kind of coincidence is that?

Another article on 2 May, quotes former CIA director James Woosley sounding the alarm about the EMP threat. Joseph Fara on WorldNetDaily (thanks Howard) writes about the testimony Woosley's testimony to the House International Terrorism and Non-Proliferation Subcommittee focused on the threat posed by Iran and the need for action on hardening the US electrical grid. The timing of this story is interesting.

Could all this be scare mongering? Could al Qaida really knock out much of the nation with a nuclear-tipped SCUD? Well, that depends. Lets just take a simple look at the physics. Nuclear detonations produce gamma radiation -- lots of it. Gamma rays ionize atmospheric molecules (called the Compton Effect) which causes a powerful electomagnetic field. This field can cause electrical voltage in any conductive materials -- wiring, generators, electronics -- pretty much anything that would conduct electricity. The EMP causes rapid onset of voltage, like an electrical spike in the equipment, thus damaging the electronics. The strength of the EMP is mainly a function of altitude. Altitude also increases the surface area that's within line of sight. So, the higher the altitude of the blast, the greater area of ground coverage. (See the Army publication Electromagnetic Pulse (EMP) And TEMPEST Protection For Facilities for more information.) The worst thing about EMP is that the damage is likely to be permanent and widespread. The equipment or components must be replaced -- and systems necessary to effect repairs (like telephones, power grid, trucks) will be out of commission too.

A $100,000 SCUD B rocket reaches a max altitude of about 160 km (496,000 ft), with a similar range. Clearly it won't reach Kansas from the ocean, but you could certainly reach much of the coastal areas. But that altitude results in a 1,200 km line-of-sight radius (see para 2-2b). That would cover a vast area. The entire west coast of the US, from Seattle to San Deigo would fit inside a circle of 2,400 km diameter. So, aside from the difficulties of obtaining a nuclear weapon, mounting it on a SCUD and launching it from a ship, the physics seems to support such a threat.

A good offense is often a good defense, but offensive programs don't seem to solve this problem. Aside from a questionably effective missile defense program, its difficult to see what defense programs might help protect against this kind of threat.