Radio-controlled bombs used to be the biggest killer of American troops in Iraq. Now, they’ve been rendered all-but-useless. Good news, right? Like so much else in Iraq, it’s not quite that simple.

Since the Iraq insurgency began, mobile phones, garage-door openers, and remotely-driven kids’ toys have all been used to trigger improvised explosive devices from afar. In response, the U.S. military has cobbled together an arsenal of radio-frequency jammers, to interrupt the deadly signals before they can set off the bombs. At first, the jammers had all kinds of troubles. Each type of jammer would only cover a relatively small slice of the spectrum. And they’d drive friendly radio and robots haywire.

But those problems have largely been fixed, troops across Iraq report. The newer jammers have effectively killed off radio-controlled IEDs in major chunks of the country.

The explosive cat-and-mouse game continues, though. The American have built up high-tech bomb-stoppers. So the insurgents have gone ever lower-tech than before. They’ve largely turned towards so-called “command wire” IEDs to attack U.S. targets.

Pairs of insulated copper threads, some not much thicker than a hair, are buried under the Iraqi dust, and strung out for as long as a kilometer. At the end, an insurgent triggerman waits – sometimes in a buried bunker. It’s a more crude approach to killing, of course. But, barring a lucky find of wires, “there’s no way for us to defeat it,” says one bomb technician. And those wires are getting attached to bigger and bigger bombs. (Check out the picture, above, of a cement-mixer-turned-shaped-charge.) Do away with one problem, and you now have to cope with the blowback from your success.

I worry that’ll be the case on the political scene, as well. Sunni political and tribal leaders are increasingly throwing in their lot with U.S. forces here against Al-Qaeda in Iraq and other insurgent types. But, to get them to come over to our side, the American military has fed them a steady diet of anti-Shi'ite propaganda.

Arrests and killings of Shi’ite militants are announced from loudspeaker blasts; President Bush’s bellicose rhetoric towards Shi’a Iran is reported on friendly radio programs. But the majority of this country is Shi’ite. Are we setting ourselves up as the enemies of the majority here? Are we priming the pump for an all-in sectarian battle royale? It seems like a possibility.

Anyway, command-wire bombs aren’t the only IED threat over here. “Pressure plate” weapons, triggered by the smallest stress, are also in vogue here. Some are even shoved into brown ration packets, and left by the side of the road. Insurgents continue to use passive infrared sensors – like those used in burglar alarms – to sense changes in heat, and trigger a bomb accordingly. Many Humvees here are equipped with a flash-type device that can prematurely set the trigger off. But there will surely be a counter to our countermeasure.

ALSO:

* Jam-Proof Insurgents? Doubtful

* Radio-Friendly Jammers?

* Pentagon Bomb Squad Under Fire

* Top War Tech #4: Jammers

* Noah talks jammers on PBS