Iran Deal Forecast No. 2: Dirty Bombs in American Cities

This is part of a series on scenarios developing out of the new Iran deal. The first of this series looked at the best case scenario, which still leaves Iran as a nuclear power with hegemony from Teheran to the Levant, but facing a massive regional arms race that threatens a huge war in the Middle East. This piece will consider the first alternative scenario, one in which Iran cheats on the deal in one of several ways. The first way we will consider is the possibility of dirty bombs.

A dirty bomb is a radiological weapon rather than a nuclear weapon per se. It is achieved by combining radiological material with conventional explosives. The detonation spreads the radioactive material over a wide area. According to the Federation of American Scientists, an organization founded by many of those scientists who worked on the Manhattan Project, a dirty bomb’s death rate will be much lower than a nuclear attack due to the fact that only around a millionth of the radiation will be released, as well as far less plain energy from the explosion. However, the death rate could still be quite high if evacuation is not carried out in a timely manner. Even once evacuation has occurred, it is still unclear just how long an affected area would need to remain evacuated, or what standards would have to be achieved before people could re-inhabit the area.

For this reason, a dirty bomb attack on the United States would be effective but far from crippling. There are a few targets, such as Manhattan, that it would be expensive to abandon for several years. Nevertheless, America has the potential to resettle large internal refugee populations and absorb them into local communities. By contrast, dirty bombs pose a particular threat to Israel, a country with a very small land area. A dirty bomb in Tel Aviv would be devastating to the nation’s economy, and the refugee problem would be much more difficult to tackle.

How difficult would it be to make and deploy such a bomb? Even Iran’s stores of highly enriched uranium would not be ideal material for such a bomb according to the Congressional Research Service. “Technical experts rarely if ever consider uranium as an RDD material because the amount of radiation emitted per gram is extremely small, most of its gamma rays are of relatively low energy, and it poses less of a biological hazard than plutonium. Plutonium could be used in an RDD because of the biological hazards from alpha particles if inhaled.” Iran has plutonium, especially ‘spent fuel’ from its Arak reactor which is still capable of being used to build a bomb. Under the terms of the deal it is required to ship it out of the country. This movement of the stockpile would provide a relatively easy opportunity for a false-flag “theft” by an allied terrorist group, which would permit easy conversion to dirty bombs plus plausible deniability in the event that such bombs were used.

The CRS report goes on to say that a terrorist group would be unlikely to build a plutonium bomb because a terrorist group seeking a true nuclear device would not likely squander any plutonium it was able to obtain. However, in this scenario the attainment of a true nuclear device is a given: Iran will certainly obtain one at least once the agreement period ends. All that is wanted in this scenario is an ability to strike powerfully in the meantime.

Therefore, this scenario is rated as a strong possibility. It would be easy to arrange the ‘theft’ of plutonium given Iran’s ties to existing terrorist groups. Building such a weapon poses no further technical barriers given access to the plutonium. Israel provides an excellent target for such a weapon. Getting the weapon into position would not be difficult given the effective control of western Syria by Iranian proxies in many areas. Finally, Iran’s ability to employ the weapon deniably through a proxy force is especially attractive. By electing a smaller, newer militia as the actual bomber, world reprisals would be channeled against a disposable and easily-replaced force. Cost to Iran would be close to zero, but the effect against Israel would be incalculable.