DENVER -- A land mine expert in Denver described the deadly devices as the single most insidious problem American military forces must confront.

A land mine exploded in Afghanistan Sunday, and Marine Cpl. Christopher Chandler of Aurora, Colo., lost his foot. Two others, Sgt. Adrian Aranda, 22, of El Paso, Texas, and Lance Cpl. Nicholas Sovereign, 20, of Battle Creek, Neb., suffered hand and head injuries, officials said.

Peter Van Arsdale has studied land mines, and he's met people who've been maimed by them. He thinks the explosives may be just as dangerous to our military as the al-Qaida soldiers still at large.

Van Arsdale said that what happened to Chandler was no surprise. Land mines are a sad reality in war zones like Afghanistan, he said.

"A land mine doesn't discriminate between a soldier, a civilian, between an innocent or a non-innocent, between a good guy or a bad guy. They don't discriminate," he said. "It's horrific."

Van Arsdale has spent a lot of time in Bosnia, where, as forces found out in 1996, minefields are everywhere. It is how one side frightens, damages or kills the enemy.

"It doesn't require sleep, food, medical aid, attention -- you put it in the ground, and it's there for life," a soldier in Bosnia said. "It's as much a part of their life as I-25 and I-70 is for the folks back home."

"They're so ominous, so deadly, so negative, that in some places these have been given names like a pumpkin or a squash. Something you'd find in our garden," Van Arsdale said.

Mines are a lot harder to pluck out of the ground, though, and Van Arsdale has heard, "that it is 10 times easier to plant a mine than to remove that same mine."

That's why there are millions of mines left all around the world, still getting far too little attention.

"You might expect fire, gunfire -- you won't expect a land mine," Van Arsdale said.

There are an estimated one million land mines still believed to be underground in Bosnia.

As for Chandler, Van Arsdale said that with the advances in prosthetic technology, he expects a very bright future for the injured Marine.

It's estimated that more than 110 million active mines are scattered in 70 countries.

Every month, more than 2,000 people are killed or maimed by mine explosions. Most victims are civilians.

While mines are priced at just $3 to $30 a piece, the cost to the international community to neutralize them ranges from $300 to $1,000 each.