* Portrait: Mario Hugo * In the past, malefactors seeking to enrich uranium to bomb-grade quality needed either a highly conspicuous industrial plant or specialized equipment that was hard to obtain and relatively easy to monitor. But there's a new method on the horizon, and it's potentially far easier to hide.

For the past four years, Charles Ferguson has been tracking the progress of a technology known as laser isotope separation. Still experimental, it requires only a warehouse-sized space and the kind of lasers within reach of a high school science geek. "The A. Q. Khan network is old-school," Ferguson says, referring to the Pakistani scientist who sold bomb secrets to Iran, Libya, and North Korea. "The next Khan network could use this new technique."

WMD experts often overlook laser enrichment because it's not yet productive enough for industrial use. That's a serious mistake. In 2002, dissidents exposed laser experiments in Iran; at least a dozen other countries are known to have dabbled in the technique.

Bottom line: The US needs to develop its own small-scale laser-enrichment operations, which it could study to learn more about the telltale signs of illicit setups. For example, key equipment used for the faux projects could then be flagged for additional monitoring. If authorities can learn to track these small-scale operations, they have a decent chance of bringing the clandestine potential of laser uranium enrichment in from the cold.

Bomb Factories

Uranium enrichment facilities are getting smaller—and easier to hide.

Gaseous Diffusion

This Cold War-era method of enriching uranium is expensive and difficult to conceal. It consumes large amounts of energy (which can be monitored easily) and requires industrial facilities of several acres, almost always conspicuous in satellite imagery.

Gas Centrifuge Separation

This process takes less space and energy than diffusion but poses other inconveniences to would-be proliferators. Few manufacturers are capable of producing the necessary precision-tooled centrifuges, a fact that makes equipment easier to track.

Laser Isotope Separation

Off-the-shelf technology can be used to run this emerging enrichment method. It takes relatively little space and consumes virtually untraceable amounts of energy, so a secret laser separation facility can operate in an unassuming warehouse.

Charles Ferguson is Senior Fellow at the Council on Foreign Relations.

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