In early 1943, Britain’s Bomber Command had been wrestling with the thorny problem of how to breach two critical dams in the Ruhr valley, cutting electricity production and incapacitating industrial production. Taking them out was a high priority of the war cabinet and Bomber Command.

 

But the problems were daunting. The dams, the Eder and the Mohne, were heavily protected with anti-aircraft batteries, and bombing at the time lacked precision. Bomber Command knew that it had to deliver its explosives to the lower part of the dam walls, if they were to be breached.

 

The solution came from a scientist and engineer, Barnes Wallis, who watched children skipping stones on water: Drop the bombs well away from the dam walls and have them bounce to the wall, sink and explode. Simple technology to the rescue.

 

The bombs would be circular and would be rotated so they hit the water, spinning backward but with overall forward motion. Like a stone skimmed along the surface of a pond they would travel to the wall, sink and detonate at the foot of the dam.

 

The scheme was fiendishly clever and extremely dangerous. It was conceived in January 1943 and executed on May 17, 1943.

 

To avoid detection, waves of bombers flew across Holland into Germany, maintaining an altitude of 100 feet and making their runs at 60 feet above the water. Many aircraft and their crews were lost, but the Eder and Mohne were breached, wrecking havoc in the Ruhr Valley.

 

There is a lesson here in how to deal with nuclear proliferation: Call off the politicians and the commentators and send in the scientists and engineers.

 

With Iran and North Korea, the West is not only suffering huge frustration but its impotence is revealed, tempting every other aspiring nuclear power to forge ahead. Neither of the options on the table is any good at all. Sanctions don’t work and reigniting war on the Korean Peninsula by bombing North Korean nuclear installations is unpalatable. As should be further destabilizing the Middle East by bombing Iran, thus consolidating hatred of the West and pushing oil above $200-a-barrel.

 

So forget about bombing and sanctions. Bombing, even if it were to dent the nuclear development in the countries concerned, is clumsy, wrought with unintended consequences and calculated to produce years, if not centuries, of resentment.

 

Yet morally, those who are in the nuclear club are obliged to keep their awful institution small. Preemptive action is reasonable but it needs to be stealthy and, ideally, anonymous. In this case, the moral weight is on the side of intervention.

 

There are many ways of enriching uranium, which involves concentrating the fissionable isotope, uranium 235, by stripping away the dominant isotope, uranium 238. The preferred way is using gas centrifuges, which is the way Iran has chosen, To understand the technology, think of a cream churn: Rather than being filled with milk these vessels are filled with a gas, uranium hexafluoride, and spun at 1,500 revolutions a second in batteries of hundreds of centrifuges.

 

These machines have two important vulnerabilities: They are so highly engineered that supposedly a fingerprint can throw them off and initiate failure, and they consume a lot of electricity.

 

Electric systems are vulnerable to cyber-attack, if they are computer- controlled (almost certainly the case in Iran and probably not in North Korea). Iran, which is apparently working toward a highly enriched uranium weapon, is vulnerable through its centrifuges–a cyber-attack on its electricity supply, causing wild functions in voltage, could be damaging, as could harmonic resonance and vibration, if these can be delivered secretly.

 

North Korea is more problematic because they already have a weapon and it is unclear whether they stuck with their original plan to use plutonium from a Soviet-era reactor or whether, as they said, they switched to uranium enrichment. These are the two paths to making a weapon: plutonium or highly enriched uranium.

 

With North Korea–so paranoid and insecure–their vulnerability is with their delivery rockets. The West’s imperative: find a way of messing with their guidance systems. If surreptitiously their rockets could be destroyed early in flight, or redirected back towards their launch pads, the Pyongyang military might rethink their whole program.

 

Bombs skittering across the surface of German dams in 1943 point to the potency of technological solutions–and a third way.