The young woman brushes her metal detector over coarse, dry grass in a field near a primary school. Against the sound of children playing, the machine beeps as she searches for unexploded bombs dropped by American aircraft four decades ago.

Most of those were cluster bombs – shells that open midair scattering tennis-ball-sized "bombies," as they are known all over Laos. About 30 percent of them failed to explode upon impact, and instead remained buried in the earth. On average, one person a day is injured or killed in some part of the country by unexploded ordnance.

Cluster bombs affect about two dozen nations, from Afghanistan to Zambia. But it was Israel's use of the weapon in Lebanon in August 2006, causing more than 200 casualties over the following year, that spurred members of the international community to act.

On Aug. 1, the Convention on Cluster Munitions comes into force under international law. Countries that have ratified the treaty will be required to cease production of cluster munitions, dispose of stockpiles, and clear contaminated areas. The first gathering of the 106 member states will be held in the Laotian capital in November.

Why the US won't sign the treaty

Neither Israel nor the United States will attend. In fact, the US, Russia, China, India, Pakistan, Brazil, and Israel are not signatories to the treaty. The US, among others, has argued that cluster bombs are an effective military tool that saves their soldiers' lives. The US has also argued that it's shifting to "smart" cluster bombs that self-destruct or deactivate, reducing the risk to civilians.

Laos, the most bombed country in the world per capita, strongly backs the treaty. Between 1964 and 1973, the US dropped more than 2 million tons of ordnance in a campaign kept hidden from Congress and the public. Since then, about 20,000 civilians have been maimed or killed by unexploded bombs, according to Legacies of War, a Washington-based group that raises awareness about America's "secret war" in Laos.

Clearing the fields of Laos

Ping Souvanton's brother was one of those victims. She now works for Mines Advisory Group, and leads the all-female team clearing this field outside the school in central Laos.

A few years ago, while farming with his parents, Ms. Souvanton's 9-year-old brother struck a "bombie" with his hoe. He died in the explosion.

"It makes me angry," she says in an interview at the school site. "Even though the war is over, the bombs still kill people."

The country has also suffered huge economic losses, says Maligna Souvignongs, who heads the government agency that oversees bomb clearance. Laos is primarily an agricultural economy, and development has been hindered by the lack of access to farmland contaminated by cluster bombs.

"Those contaminated areas coincide with the poorest districts of the country. So if you would like to eradicate poverty, you have to clear those areas. If you would like [people] to produce enough food to feed their family, you have to clear land," he says.

Mr. Souvignongs estimates it will take Laos 100 years to rid itself of unexploded ordnance at the current rate. And he points out that international funding for clearance fell last year.

But he is optimistic that more funding will become available after the treaty comes into effect. He adds that though the US has not signed the treaty, it could increase clearance efforts.

Money for bombs, but not for cleanup?

Indeed, figures show a dramatic contrast between the amount the US spent bombing Laos and the amount spent clearing away their lethal legacy. The US currently contributes about $5 million per year to cleanup efforts. Every single day for nine years it spent about $17 million (in today's dollars) bombing Laos, according to Legacies of War.

More American diplomats and politicians are beginning to agree that their government owes Laotians much more than it has provided. On July 15, five former US ambassadors to Laos sent a letter to Secretary of State Hillary Rodham Clinton urging her to increase funding for clearance efforts. "Only steady US leadership and additional resources will ultimately bring this sad and unfortunate legacy of the Vietnam War to a safe and honorable conclusion," the ambassadors wrote.

On April 22, Congress held its first hearings into unexploded ordnance left over from the bombing of Laos. Channapha Khamvongsa, the executive director of Legacies of War, testified, calling for the US to commit $10 million annually over the next 10 years.

"I hope the US will do the right thing and address this problem once and for all," Ms. Khamvongsa says."

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