Buried bombs can be destroyed, but not defeated.

• Author: Erwin, Sandra I.

The weapons of choice of U.S. enemies, improvised explosive devices, are like deadly viruses that mutate in reaction to vaccines. They cannot be wiped out, only temporarily thwarted.

"I liken the IED a little bit to malaria," said the Army's Chief Scientist Scott Fish. "We have a lot of solutions to malaria. But it adapts and evolves over time."

Over the past decade of war, every time the U.S. military has come up with new ways to block radio signals that detonate bombs, or new techniques to detect and destroy IEDs, insurgents have struck back with deadlier means to blow up armored vehicles and its occupants.

The Pentagon's science and technology community has not exactly given up on finding new anti-IED weapons, but officials have acknowledged that they will forever play catch-up. "IEDs are not going to go away," Fish said at a recent conference of military reporters. "They are here to stay," he said. "Our enemies will continue to evolve IEDs."

So far the most successful antidote has been heavily armored trucks that can withstand large explosions and protect crews. Because IEDs are easy to build and bury, and tough to find, armor remains the best available countermeasure.

The reasoning is that if U.S. troops and equipment can be made more survivable, enemy fighters will have to make progressively larger bombs to kills their targets. Larger explosives would be deadlier, but easier to discover, and would increase the odds that U.S. forces could dodge them.

"We're looking at how to create systems to survive large IED attacks," Fish said. "The larger ones create a lot of damage but are easier to find, [compared to] small IEDs which are a bit of a test."

In Afghanistan, bomb attacks have reached historically high levels, according to Army Lt. Gen. Michael D. Barbero, the director of the Pentagon's Joint IED Defeat Organization. In June and July alone, JIEDDO recorded 1,600 "events," he told an industry conference.

Barbero said he expects that IEDs will remain a scourge for decades.

IED casualties were partially contained in recent years as troops in war zones traded in their light-skinned Humvees for the much heavier mine-resistant ambush protected, or MRAP, trucks.

But roads in Afghanistan are so mine-infested that driving trucks can become a game of Russian roulette. Route-clearance experts, explosive ordnance disposal units, are in such high demand that they cannot possibly clear every road. Even when an EOD unit is available, it can take...