Do Terror Groups Have Better Engineers?

From Restraint: A New Foundation for U.S. Grand Strategy by Barry R. Posen (Posen is Ford International Professor of Political Science and director of the Security Studies at MIT):

"Though military analysts believe that the Vietnamese were much more competent militarily than the Iraqi insurgents, the Iraqi insurgents appear to be twice as efficient killers.  In Vietnam roughly 50,000 Americans and 250,000 South Vietnamese troops died versus 1.1 million communist troops.  The United States suffered about 4,400 dead in Iraq, and Iraqi security forces around 9,300 versus as many as 25,000 insurgents.  The exchange rate has deteriorated from 4:1 to 2:1, largely due to the cunning employment of command-detonated IED's to kill Americans and their allies without having to expose oneself to counterfire. Since Vietnam, the United States has invested heavily in military technology, which significantly lowered the personnel costs of the Iraq war relative to Vietnam and probably forced Iraqi insurgents to avoid the pitched battles with Americans that the Vietnamese sought.  The Iraqi insurgents countered with their own technology - the improvised explosive device - and engaged in a seesaw innovation battle with U.S. detection and jamming gear."