Along a path at the edge of a weed-ridden farm in Cambodia, a man listens carefully as he sweeps his metal detector over the ground. When the detector's squealing tone signals the presence of buried metal, the man stops, repeats the sweep, and carefully marks the spot. Soon a second worker follows and lies on the ground, his head an arm's length from the marked spot, gently probing the ground with a stick. Both men are experienced deminers, one a retired British Army veteran far from home, the other a local resident trained to find mines. Both know well the cost of error: sudden serious injury or death.

After probing the hard dirt with concentrated care for about 20 minutes, the prone worker judges by sight and feel whether he has hit the rounded metallic body of a buried mine or merely the random detritus of an old battlefield: a bullet, a piece of shrapnel, a length of wire, an empty tin can. He knows that in some fields the odds are as low as one in a few hundred that the detected metal is actually a mine, but his partner's metal detector cannot distinguish an explosive device from any other object that holds a fraction of an ounce of metal.

Whatever it is, the metallic object must be carefully exposed to reveal its form and color. If it is a mine the workers will place a modest explosive charge beside it, unspool long wires, and retreat 100 yards to blow it up. Then the task will repeat itself: the operator of the metal detector will resume his patient sweeping, listening for signs of the next buried metallic object in his path while his partner waits for his next tense trial in the dirt.

According to United Nations estimates, more than 100 million mines lie buried around the world, outlasting their wars, abandoned long ago yet awaiting their unintended victims for as long as decades. An anti-personnel mine costs only a few dollars to produce, but it now costs a hundred times that sum to remove it. In Cambodia alone, where some of the world's densest minefields lay, roughly 10 million mines lurk within an area the size of Missouri. Last year three thousand workers cleared landmines from 12 square kilometers of Cambodian land at a cost of $8 million. They were not overpaid. But at that rate, even if someone were willing to foot the bill, demining Cambodia would take some 10,000 years. To make matters worse, participants in today's conflicts are emplacing new mines at a rate 10 or more times the current yield of the deminers, who now clear perhaps 100,000 mines per year worldwide. A chronic and growing crisis is at hand.