On March 15, Saudi warplanes attacked a crowded marketplace in the northern Yemeni Shi’ite town of Mastaba, killing 119 civilians. The attack was among the deadliest Saudi strikes on civilians in Yemen since the war began last year, a conflict which has killed in excess of 3,000 civilian bystanders, mostly in airstrikes.

Human Rights Watch, which investigated the incident, has found evidence that the deaths were caused by a US-made bomb, a GBU-31 satellite-guided bomb. US sales to Saudi Arabia in November included 400 such bombs.

Human rights groups have been increasingly critical of the US and other Western nations for massive arms sales to Saudi Arabia, noting the huge number of civilians they’ve been killing, and UN reports have accused the Saudis of deliberately targeting civilians in many cases.

The EU has even gone so far as to pass a non-binding resolution urging its members to stop sales to the Saudis, though by and large this hasn’t happened yet. The US has been heavily involved in arming the Saudis, and has also participated in the war on Yemen, refueling Saudi bombers and providing ships to take part in the naval blockade.