The moral logic of suicide bombing.

Are suicide bombings increasing around the world? If so, why? What can we do about it?

The latest warning sign comes from data reported a week ago by Robin Wright of the Washington Post:

Suicide bombers conducted 658 attacks around the world last year … more than double the number in any of the past 25 years … More than four-fifths of the suicide bombings over that period have occurred in the past seven years, the data show. The bombings have spread to dozens of countries on five continents, killed more than 21,350 people and injured about 50,000 since 1983 … [S]ince 1983, bombers in more than 50 groups from Argentina to Algeria, Croatia to China and India to Indonesia have adapted car bombs to make explosive belts, vests, toys, motorcycles, bikes, boats, backpacks and false-pregnancy stomachs. Of 1,840 incidents in the past 25 years, more than 86 percent have occurred since 2001, and the highest annual numbers have occurred in the past four years.

To make sense of these numbers, we need to understand how they connect to recent developments in military technology. If you follow the daily Human Nature News updates, you've seen several such developments over the past month. Here's a short list:

1. U.S. commanders are seeking authority to launch drone attacks on Pakistani militants.

2. A Georgian drone was shot down by Russia, but not before relaying video that identified the aircraft that had fired on it.

3. The U.S. military has launched an initiative to regenerate lost body parts.

4. The United States is developing walking military robots.

5. Scientists are learning how to remotely detect explosives using chemicals.

6. We're developing a way to detect bombs by tethering animals to robots.

How do these developments fit together? What do they mean? They fit into a framework I sketched two years ago and updated last fall. Here are some of its key concepts:

1.Morality is expensive. It's easier to destroy things than to preserve or build them. It's even easier when you don't care whom you kill. In Iraq, a major purpose of suicide bombings and "improvised explosive devices" has been to kill enough Americans with enough regularity to make the public demand that our troops come home. The bombers have the edge because they care less about death than we do.

2.Machines are crucial to defeating terrorism. The main advantage of machines isn't that they're brilliant. It's that they don't bleed. We can't stand death, so we replace our soldiers with lifeless proxies. Nobody demands a pullout because some bomb-defusing gizmo got blown up in Baghdad today. And in general, the ideal mode of warfare is hunting our enemies in their own territory at little or no risk to ourselves.

3.Machines are still primitive. The process of engineering machines to see and move the way we do is moving along slowly. In the case of IEDs, the United States has found that humans, particularly those who have hunting experience, are more agile and discerning.

4. Machines can be combined with animals. Animals have the agility and sensory precision that machines lack. Animals have hunting experience. Animals, like machines, are regarded as morally expendable. That's why the military has explored remote control of IED-sniffing dogs through radio receivers attached to their collars.

Here's how this framework makes sense of the current news reports. First, the United States wants to use drones against Pakistani militants because it's too politically dangerous at home and in Pakistan to have our troops doing the dirty work on the ground. We need to operate from a safe distance.

Second, as the Georgian case illustrates, there are going to be a lot of drone shoot-downs in the years ahead. Shoot down a plane with a live pilot in it, and you risk war. Shoot down a drone piloted by some guy in a remote booth, and the worst you risk, probably, is condemnation. But don't expect to get away with it completely: Video-equipped drones, unlike people, can incriminate you even as you kill them.

Third, the United States is trying to reduce its fatalities and casualties in every possible way. Military medicine is already saving the lives of soldiers who would have died in previous conflicts. Yesterday's death is today's wound. Now, with tissue regeneration, we're raising the ante: Today's "permanent" wound will be tomorrow's bad memory.

Fourth, we're trying to insulate American soldiers altogether bydeveloping robots to absorb risks previously shouldered by troops. Likewise, we're mechanizing bomb detection.

Fifth, we're trying to upgrade the agility and decision-making of our military devices by entrusting them to living creatures we regard as expendable: animals.