The organizations that provide the money for bomb building, and help with obtaining materials (there's a black market for everything in Iraq, everything), are also evolving. They have to, as the "management" of the IED campaign have look been considered prime suspects, and much sought after by U.S. troops and Iraqi police. But you don't hear much about this in the media, for the simple reason that American intelligence does not want to let on how much it knows and how close it is getting to the remaining IED kingpins. That's very much a war in the shadows, and one that extends into neighboring countries. A number of the IED gangs have been destroyed, or severely damaged. But while attempts are made to decapitate the IED campaign, work continues at the grassroots level to detect, disable and destroy those that are placed. Currently, there are 10-12 American combat casualties a day, with two or three of them being fatal. About two thirds of these casualties are caused by IEDs. Troops are most vulnerable to IEDs when they are on combat operations. The supply and transportation troops have their regular routes (especially the MSR, or Main Supply Route highways), very well covered. IEDs rarely get a chance to go off, or even get planted, on those roads. But for Sunni Arab areas, not visited until recently by American troops, there are more opportunities to place an IED that won't be discovered, and will get a chance to kill and wound Americans.
Actually, the biggest victims of IEDs are Iraqis, especially civilians. The terrorists must go to great lengths to place IEDs in populated areas, where all the structures and clutter along the roads leaves more hiding places. But the local Iraqis are not keep on having a large bomb go off in their neighborhood. The terrorists often don't give the locals much choice. After all, terrorists know how to terrorize, and they usually start with uncooperative Iraqis living around them. IEDs place in rural areas are much easier to spot by the Americans, and all their UAVs, electronic gadgets and sharp eyed soldiers.
The Iraqi Sunni Arab terrorists believe that if they go on enough days, causing a dozen or so American casualties, will eventually cause the Americans to get discouraged and go home. This worked in Vietnam, although it didn't work for the Japanese during World War II. So it's not a sure thing.
The most successful Iraqi weapon has been the roadside bomb, otherwise known as IED's (Improvised Explosive Devices). Over the last two years, the Iraqi terrorists have largely scaled down other forms of attack (assault rifles, RPGs, rockets), and concentrated on the IEDs. There's a very good reason for this, building and placing an IED is much less likely to get you killed, than having a shootout with American troops. The terrorists will still attack with rifles and RPGs, and still get killed in large numbers when they do so. So a great deal of effort, and resources, has gone into building more, and better, IEDs. In the last year, the number of IEDs used has grown from about 20 a day, to over 30 a day. The only downside to this is that over 90 percent of IEDs used, fail to hurt anyone. Instead, they are discovered and destroyed, or dismantled by an American forensics team, in order to help in the search for the groups that specialize in building IEDs. That raises another important issue; IEDs are big business in Iraq. Most of the Iraqis making and planning these bombs are not doing it for free. They get paid, and the bomb building industry generates over ten million dollars a year in revenues for Iraqi individuals and contractors. For a Sunni Arab who once worked for Saddam, this is one of the few good employment opportunities available. Moreover, the low risk aspect has brought out the "Geeks-for-Saddam," crowd and resulted in many snazzy instructional DVDs and videos for wannabe bomb makers. Excellent graphics, and everything is in Arabic. Many of these items have been captured, along with a few of the geeks. The educational effort was supported by the terrorist leaders because it was obvious that, without constantly improving the bomb designs and planting tactics, the failure rate would soon get to 99 percent, or worse.