In this blueprint for a national nightmare, an enemy nation or terrorist group would launch a missile containing a powerful nuclear weapon. The device would explode at high altitude above the U.S. and release a burst of radiation that would interact with the Earth’s magnetic field and atmosphere—including the ionosphere, the thin upper layer filled with free electrons, which facilitates radio communications. As a result, a powerful electrical current would radiate down to the Earth and create additional currents that would course through man-made electrical circuits as well. Electrical infrastructure and electronic devices would receive severe shocks, causing severe, widespread damage. A federal commission of scientific and military experts convened by Congress in 2004 warned that an EMP attack could cause a massive blackout that would affect phone systems, electric power transmission, factories the financial system, and transportation. “Depending on the specific characteristics of the attacks, unprecedented cascading failures of our major infrastructures could result,” the commission warned. “In that event, a regional or national recovery would be long and difficult and would seriously degrade the safety and overall viability of our Nation.” The commission noted that “the longer the outage, the more problematic and uncertain the recovery will be.
Our vulnerability to EMP attack was first discovered back in 1962, during a military exercise, Starfish Prime, in which a missile containing a 1.4 megaton nuclear warhead was detonated at a height of 248 miles over a remote area in the Pacific Ocean The blast had an unexpected effect, disrupting radio transmission as far away as California and Australia for several hours. It also damaged and ultimately disabled at least six orbiting satellites--including Telstar I, the satellite that transmitted the first live TV broadcasts from the U.S. to Europe and back again. U.S. officials didn’t bother to develop any defenses against the EMP during the Cold War, because they assumed that the threat of a retaliatory nuclear attack was sufficient. Since then, however, new menaces have emerged—rogue states such as Iran and North Korea and terrorist groups, whose volatile leaders might not be as easily deterred. To make matters worse, today’s U.S. is far more dependent upon electronic gadgetry than it was 50 years ago.
While some doomsayers, such as former U.S. House Speaker and Presidential candidate Newt Gingrich, have sounded the alarm about the threat of EMP, others have doubted that such an attack would really be as dire of a threat. In a 2003 paper, Electric Power Research Institute staffer Mario Rabinowitz concluded that an EMP generated by a nuclear blast would be no more harmful to the electrical grid that natural events such as lightning storms, and notes that in the 1962 Starfish Prime test, the telecommunications system and power grid in Hawaii was not seriously damaged. A 2008 report by the Congressional Research Service, however, noted that even a less-than-devastating EMP attack could still cause a lot of damage. An attack on the Washington DC-Baltimore region that only damaged 10 percent of communications systems and the electrical grid and 20 percent of electronic devices would still require a month of recovery time and inflict as much as $34 billion in economic losses.