An Arab coalition led by Saudi Arabia has been launching air strikes in Yemen after Iran-backed Huthi rebels overran the capital Sanaa in September 2014, and later advanced to seize most of the country.
More than 6,400 people have been killed in the conflict and almost 2.8 million displaced since operations began in March 2015.
Human rights groups have condemned the bombing campaign, and called on the US to stop selling weapons which are then unleashed by the Saudi kingdom on populated areas, killing thousands of civilians.
More recently, campaigners have called out president Obama on the use of US cluster bombs by the Saudi military – a move which could be responsible for unlawful killing on a large scale.
Belkis Wille, the Yemen researcher for Human Rights Watch, describes the bomb’s devastating effect on the ground:
“When cluster bombs land they deploy sub-munitions. We often see that these sub-munitions don’t explode upon impact. They lie on the ground, and become de facto land mines. An unsuspecting passer-by, often a child, picks up this thing that looks interesting, and that’s when it explodes.”
Because of the risk cluster munitions pose to civilians, over a hundred countries have signed a treaty banning their use. But neither the US nor Saudi Arabia are on that list.
State Department officials have vowed to put pressure on their Saudi counterparts over “reports of civilian harm” in Yemen, and the US Congress has introduced stricter laws on cluster munitions exports.
Under the current legislation, they cannot be sold to countries which use them in or near civilian populated areas, and sales are restricted to one specific type of cluster bomb, which should have a fail rate of less than one per cent, to avoid them landing unexploded.
But Belkis Wille says the legislation is insufficient, and that cluster bombs should be banned altogether.
“Theoretically the bomb I was speaking about meets that standard, and that’s why it’s allowed to be sold by Congress. I have seen that bomb across Yemen with canisters still attached which had not exploded upon impact. As a result we call for the complete ban on cluster munitions. That has to be absolute.”
Under Barack Obama, who received the Nobel Peace Prize in 2009, there has been no major shift in policy on the use of cluster munitions.
"These human rights issues tend to be institutional problems rather than party-political ones, whether it’s a Republican or a Democrat”, says Andrew Smith, from the Campaing Against Arms Trade (CAAT).
“I think there are many ways in which Obama has been a more enlightened president than his predecessor, but I’m not sure the arms trade is one of those areas.”
In the coming days it seems unlikely the issue will attract much attention among the main belligerents in Yemen.
They will be focusing primarily on the ongoing peace talks in Kuwait, which finally got underway on Thursday, after the delayed arrival a delegation of Yemeni rebels.
The United Nations has been pushing the negotiations, in an effort to end the war between the Huthi rebels and the Saudi-led coalition backing Yemen's government in exile.