Editor's note: This film is no longer available online.

Ahmed will never forget the day in 2018 when Saudi-led coalition jets hit a school bus in Yemen's Saada - killing 51 people, including 40 children. One of them was his 11-year-old son, Ali.

Ahmed was at the market, heard the bombing, and immediately went to assist the injured.

"I didn't know what the target was. People said the school bus was hit. I ran over to help the kids," he says. "I was told that my son was lying under the bus. I saw his red coat and yellow scarf. I knew right away it was my son."

The coalition called the attack a mistake, saying their target was Houthi rebels - the armed group that overthrew Yemen's government and has controlled the northwest and the city of Sanaa since 2014.

The coalition, led by Saudi Arabia and the UAE, entered the conflict in 2015 to support Yemen's internationally recognised government in its fight against the Houthis.

By continuing to sell weapons to Saudi Arabia - or other members of the coalition - that are likely to be used in unlawful coalition attacks in Yemen, the UK and France ... are risking complicity in future unlawful coalition attacks.

Kristine Beckerle, Human Rights Watch

It has pounded Yemen relentlessly: there have been more than 19,000 airstrikes since 2015, and one-third of these have struck non-military targets - homes, hospitals, schools, markets and mosques.

Fighting from both sides is estimated to have killed more than 50,000 Yemeni civilians during the same period.

According to the United Nations, Yemen today is the world's worst humanitarian crisis.

In 2018, the UN appointed a panel of experts to examine the coalition blockade on Yemen and the impact of the thousands of airstrikes launched against civilians there. It concluded that these practices could qualify as war crimes.

It pointed not only at Saudi Arabia and the UAE, but also at the parties supplying the coalition with weapons, based on a multilateral treaty regulating arms sales that has been in force since 2014.

Saudi Arabia buys its weapons from the United States and the United Kingdom, as well as from a number of European arms manufacturers, led by French and German companies.

Officially, the use of these European weapons is compliant with international law. But the reality is far more complex.

"By continuing to sell weapons to Saudi Arabia - or other members of the coalition - that are likely to be used in unlawful coalition attacks in Yemen, the UK and France ... are risking complicity in future unlawful coalition attacks," says Kristine Beckerle, a Yemen researcher with Human Rights Watch.

The European parliament has called for a suspension of arms sales to Saudi. Although five EU member states have stopped selling war weapons to the kingdom, its five biggest suppliers, led by the UK, have not. 

While a British appeals court ruling in June found British arms sales to Saudi Arabia that were used in Yemen's war were unlawful, it has not technically stopped the UK from selling the arms, but merely forces the UK to review its procedure for granting arms licences.

In this film, we reveal details of the shadowy world of the so-called legal arms trade, the double-discourse of our democracies, and the shortcomings of European governments. And we pose a fundamental question: by pursuing trade with Saudi Arabia, are European countries complicit in war crimes?

Source: Al Jazeera