When you're a member of a club that includes Saudi Arabia, Iran, Zimbabwe, Pakistan, Russia, China, Equatorial Guinea, and Turkmenistan, you may very well be doing something you shouldn't be doing. And that is the motley crew the United States finds itself alongside in refusing to sign the Convention on Cluster Munitions, an international treaty prohibiting the use, transfer, and stockpiling of cluster bombs.

Cluster bombs scatter hundreds of fist-sized "bomblets" over a large area. But up to 30 percent of the bomblets don't explode, which means they litter war zones for years after the bombing is done. They are then often accidentally detonated by civilians — including curious children who pick them up thinking they're toys. In Vietnam alone, as many as 300 people are still killed every year by them. Some 270 million cluster bombs were dropped on Laos in the 1960s and 70s, which means there are as many as 80 million bomblets that may have been left unexploded. Up to 4 million cluster submunitions were dropped in Lebanon by Israel in 2006, meaning as many as 1.2 million may have been left unexploded.

The numbers of civilian casualties cluster bombs cause even decades after being dropped — often more than are killed by land mines — ought to mean that cluster munitions are relegated to a bygone era of indiscriminate war. Their continued use is met with almost universal revulsion, and the Convention on Cluster Munitions banning their use has 113 signatories. Even countries that haven't signed the treaty are still bound by customary international humanitarian law, specifically that "the use of weapons which are by nature indiscriminate is prohibited."

Amnesty International believes that cluster munitions rank among such inherently indiscriminate weapons. "They cannot be directed at a specific military target, and their effects cannot be limited as required by international law," a spokesperson told us. "So we would argue that even states who are not party to the Convention on Cluster Munitions would violate international humanitarian law if they use cluster munitions."

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We agree, and we had assumed that only those states that relish snubbing international law still deployed them. (Although as we were to find out, they make up a big chunk of America's weapons stockpile.) We certainly hadn't expected to find US-made cluster bombs littering the countryside in Sa'dah, a province in the north of Yemen, during a recent trip to film a documentary for VICE on HBO that airs tonight. We were there to cover the Houthis, a Shia group that fought the government of Yemen and, briefly, Saudi Arabia, in six wars between 2004 and 2010. It's a conflict that received almost no mention in the international media, thanks at least in part to a media blackout imposed by the government of Yemen's former president Ali Abdullah Saleh, who at the time was backed by the US government. The Houthis claim that the Saleh regime used the news vacuum to commit serious human rights abuses.

We were driving through cloud-covered mountains dotted with stunning Yemeni houses with their unique gingerbread architecture. Our guards, their AK-47s casually stowed on the car seats, were blasting Houthi rebel music on the sound system — complete with samples of machine gun fire in place of drumbeats — when we saw a large pile of green shells by the side of the road. The detritus of the six wars are so common in Sa'dah that our guides didn't even bother to point them out, but we stopped the car and examined the shells nonetheless. They were marked with a model type, CBU-52B/B, and labels that read "US AIR FORCE."

When the CBU-52B/Bs are used, the shell — known in the arms trade as a dispenser, which makes it sound like it squirts hand soap rather than raining down deadly explosives — separates in mid-air, dropping 220 bomblets at a time on an area roughly the size of a football field. Cluster bombs are anti-personnel weapons, meant to exact the maximum possible carnage upon detonation, killing people on the ground. They are designed to have the opposite effect of the "pin-point" and "clinical" strikes that modern technology supposedly allows (but in reality often doesn't). We didn't find any bomblets next to the casings — although while lifting a shell to read a serial number, one of us found an unexploded artillery shell underfoot — but the damage they have done in the area has been devastating.

**Watch the VICE on HBO segment "Enemy of My Enemy" here: **

In 2009, when he saw airplanes crossing over the border from Saudi Arabia, Mohammed Jubran Abu Halah was 13 years old. The aircraft started dropping bombs over Saddah, a largely agricultural area in the north of Sa'dah province. Although he says that there was no fighting in the area — neither he nor his family are supporters in any meaningful sense of the Houthi movement — a number of bomblets landed in and around Al Uguum, his village. Sometime after the war ended, his father, a farmer, returned to tend to the family's land.

"There was a bomb dropped during the war that fell near my house," Mohammed said over the phone from Al Uguum, where he still lives. "It looked like a teacup. When my father found it, he didn't know what it was so he tried to pick it up." The bomblet exploded, killing Mohammed's father and his 4-year-old brother, Yahya; both Mohammed and his mother were hit by shrapnel. The family received no compensation from the government, and had to foot the bill for treatment at a hospital in Sa'dah city, several hours' drive away. While Mohammed was in the hospital being treated, the young son of a family friend picked up another bomblet, which neighbors say was the size and shape of a grenade. He was also killed.

Now 17, Mohammed can do little to help his family. "It hit me in the leg, the thigh, my left hand, and eye," he says. "Now I can see very little, I am basically blind. I am no use."

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Hamoud Gabish, the deputy director of Al Hayyat, a humanitarian organization that deals with the fallout of the Sa'dah conflict, has dedicated much of the past six years to easing the impact of both the mines left by the Yemeni Army, and the cluster bomblets, which he says were dropped by the Saudi Air Force.

The Saudis entered the Sa'dah fray in November 2009, the first combat missions undertaken by their military since the first Gulf War in 1991. In response to clashes on the Yemen-Saudi Arabia border, Saudi airplanes entered Yemeni airspace to carry out raids on what Riyadh said were Houthi military positions. According to Jane's, a defense and security analysis firm, the Saudis used European Tornado IDS and American-made F-15S aircraft.

"Most of the planes they used to drop the cluster bombs were Tornadoes," Gabish says of a series of raids that, by his estimate, resulted in bombs being dropped on 164 locations in Sa'dah. A defense contractor who agreed to speak to us as long as we didn't use his name says that if there were a choice between the Tornado and F-15S, the Tornado would be the better option to drop cluster bombs of the kind we found. Yemen has its own small stockpile of cluster bombs, but they are Russian- rather than US-made.

Amnesty International said that the casings we saw were consistent with pictures the organization had received in March 2010 from those who had fled Sa'dah. "These people, accessed and interviewed separately, said that Saudi Arabian air strikes, which began in November, were of an intensity and power not experienced before," the Amnesty spokesperson told us. "They also said the strikes took place around the clock in the days leading up to the ceasefire in February 2010. Several displaced people described seeing bomblets attached to small parachutes floating down to the ground before exploding, indicating the use of cluster bombs."

Houthi rebels pose with a US-made cluster bomb shell in northern Yemen.

The continued presence of hundreds if not thousands of bomblets in the area has devastated the largely agricultural economy. "We are afraid to go to our farms, to take our sheep out to graze," Mohammed says. "We can't work because we are afraid of this. I lost my father and my brother. What if I come across another bomb?"

Gabish says that the affected farmland is reverting back to wilderness because farmers are afraid to return. In March, he says, a shepherd in the north of the province became the latest victim of a cluster bomb, more than four years after the Saudi planes first crossed into Sa'dah. Cluster bombs are often used as "denial weapons," which make the areas on which they're dropped inaccessible, and it is possible that Saudi Arabia dropped them where they did in part to seal the border with Houthi-controlled Sa'dah. That would mean the Saudi Air Force effectively targeted civilians — a possible violation of human rights law.

In addition to Saudi Arabia, Gabish holds the US and UK accountable for the bombings and their aftermath. Both the US and UK militaries provide training and logistical support to the Saudi military, while UK and American firms including BAE Systems and Boeing — BAE led the manufacture of the Tornado, and Boeing merged with F-15 maker McDonnell Douglas in 1997 — have lucrative service and supply contracts with the Saudi Air Force. The planes themselves were supplied well before any discussion of banning cluster munitions had begun, but many of the service deals overlapped or came after the Convention on Cluster Munitions, which came into force in 2010, was signed. In 2006, for example, BAE inked a deal — still in effect — to refit and upgrade Saudi Arabia's Tornado aircraft that's worth an estimated $4.2 billion.

This is particularly problematic given that, although neither Saudi Arabia nor the US has signed on to the convention — which forbids signatories to "assist, encourage, or induce anyone to engage in any activity" related to their use — the UK government did in 2008, a year before Saudi planes crossed into Sa'dah. Since 2007, the British government has run something called the Saudi British Defence Cooperation Program, which is aimed at selling British arms and military expertise to Saudi Arabia. BAE is subject to UK law and cooperates closely with the UK government; the company "must have known" if Tornados equipped to drop cluster bombs were being used, says the defense contractor.

I asked BAE whether they knew if the Tornados on which they work were used to drop cluster bombs. "The work we undertake on the Tornado aircraft in service with the RSAF [Royal Saudi Air Force] is conducted under a government-to-government agreement between the Kingdom of Saudi Arabia and the United Kingdom," a spokesperson said. "We are satisfied that this work is compliant with the law. Legal and national security obligations prevent us from commenting on the capabilities or activities of a foreign sovereign nation." A spokesman for the UK Ministry of Defence said that the UK government had not seen any evidence to suggest that the Saudi Air Force had used cluster bombs against the Houthis, and suggested we contact the Saudis for comment. We did, and they had not responded at press time.

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"There is a need to survey the degree of contamination, warn and educate the population about the risks posed, clear the unexploded ordnance, and assist any victims," says Mark Hiznay, a senior researcher at the arms division of Human Rights Watch. "Saudi Arabia should provide, on humanitarian grounds, any information about the types, quantities, and locations where its forces used cluster munitions in Yemen." He acknowledged that the UK has been a leader in banning cluster munitions — it recently destroyed its stockpile of more than 190,000. But he added, "British companies should exercise caution in engaging in maintenance contracts for aircraft that may assist Saudi Arabia in further use of cluster munitions…. The US should immediately reexamine its exports of cluster munitions to Saudi Arabia given its apparent willingness to use the weapon in civilian areas."

The Sa'dah war wasn't the only time cluster bombs have been used in Yemen — or even the only time they were used that year. The fallout from their use in a December 2009 attack against an alleged al Qaeda in the Arabian Peninsula (AQAP) training camp in the south of Yemen that led to the deaths of 14 women and 21 children has been well-documented. In June 2010, Amnesty International released photos taken near the site of the strike of US-manufactured Tomahawk cruise missile casings that had delivered the bombs. According to Amnesty, missiles of this kind are only known to be held by the US military, and the Yemeni armed forces don't have the ability to use them. Among a group of diplomatic cables published by Wikileaks in 2010 was a report that appeared to confirm allegations that the missiles were launched from a US naval vessel. In the documents, Yemen's then-president Saleh assured US General David Petraeus that his government would "continue saying the bombs are ours, not yours."

"Besides the appalling loss of civilian life it caused, the al-Ma'jalah attack was particularly troubling because it was carried out at a time when there was no armed conflict in that area," the Amnesty spokesperson told us. "In other words, international humanitarian law did not apply, so the use of a weapon of war such as a cruise missile was completely inappropriate." Amnesty has requested information about the attack from the Pentagon, but says it is yet to receive a response. The US has defended its right to use cluster munitions largely on the basis that they make up such a large part of its weapons stockpile and would be expensive to replace, and because using targeted strikes would be less cost effective — the US military would need to use more missiles to kill the same number of people.

The State Department told us that all military sales to Saudi Arabia complied with US law. We gave them four days to respond to the allegations in this article, but a spokesman said their answers still wouldn't be ready for several more days. If we receive responses from the State Department, we'll update this story.

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The Saudi Air Force may have taken part in operations in Yemen since the 2009 attacks in Sa'dah. In 2012, Iona Craig, Yemen correspondent for the Times of London, revealed that the Saudis were taking part in airstrikes against suspected AQAP militants in Yemen. "Some of the so-called drone missions are actually Saudi Air Force missions," Craig quoted a US intelligence official as saying. It is not clear what kind of missiles were used in the attacks.

The shells we found were made in the 1960s, but both the US and UK have supplied the Saudis with cluster bombs in recent years. Last August, the US Department of Defense announced the sale of 1,300 cluster bombs to Saudi Arabia as part of an arms deal worth $641 million. The US claimed not only that modern cluster munitions of the kind now being sold, often called "sensor fuzed cluster munitions," leave as few as 1 percent of bomblets unexploded, but that they "leave a clean battlefield." But even if the 1 percent failure rate is accurate, that would still leave thousands of unexploded bomblets on the ground. Raee McGrath, spokesman on cluster munitions for the Handicap International Network, studied the use, by US forces, of these kinds of cluster munitions during the invasion of Iraq in 2003. He concluded that "the percentage of sub-munitions which have failed is higher than 1 percent. Perhaps substantially so…. [The weapon] quite clearly does not leave a clean battlefield."

The bombs must have a 1 percent failure rate or less to comply with US trade regulations.

It's odd in many ways that cluster bombs don't attract as much attention as drones, America's weapon of choice in its fight against al Qaeda and a hot topic for human rights campaigners. For all their failings, drones are fairly accurate, and the damage they cause is limited to the area of the strike site. Much of the debate in Yemen around foreign involvement in the fight against al Qaeda focuses on the fallout from the use of drones loaded with Hellfire missiles, and is mainly to do with faulty intelligence and the willingness of drone operators to launch missile strikes without considering the potential for collateral damage. For instance, a December 2013 attack killed 14 people in a wedding convoy in southern Yemen and failed to hit the actual targets of the strike, who fled when they heard the drones overhead. This raises significant questions about the way the US operates, not least about its willingness to summarily execute people thousands of miles away without trial. But at the very least, a drone strike will not result in a child disturbing a bomblet five years later and dying for absolutely no reason at all.

The Yemeni military is currently fighting AQAP in the south of the country. The government has asked for support from both the US and Saudi Arabia in what the Yemeni defense minister has described as an "all-out war." The response to the campaign has been positive both in Yemen and in the West. But little attention has been paid to the impact the campaign is having on the civilian population, or what Saudi or US support entails. The fact that Yemen, the US, and Saudi Arabia have been involved or complicit in the use of cluster bombs suggests a worrying attitude toward civilian life in the midst of fighting.

"There is nothing that suggests that the use of such weapons will not happen again," says Baraa Shiban, Yemen coordinator for UK human rights nonprofit Reprieve. "Especially with the amount of secrecy and the lack of transparency in the counterterrorism program in Yemen."

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