In his illuminating long read (‘They couldn’t do it without us’: the UK’s role in Yemen’s deadly war, 18 June), Arron Merat describes the increasingly shaky claims made by ministers that the UK is not a party to the Yemen conflict (despite the UK posting personnel to prepare and maintain Saudi Arabian fighter jets, and sending UK special forces to fight on the side of the Saudi-led coalition). Such claims are clearly designed to avoid responsibility under rules of the Geneva conventions and other international humanitarian law that bind parties to conflict.

Under the international law of state responsibility, however, the UK could still be liable for “aiding and assisting” another state that committed an internationally wrongful act or maintained a serious breach of a peremptory norm of international law. The overwhelming evidence collected on the ground by Mwatana, Ceasefire’s partner organisation cited by Arron Merat, testifies to gross and systematic violations including repeated airstrikes against schools, hospitals, markets, farms and food storage sites, far from any military objective.

Nor is responsibility for war crimes restricted to individuals who are linked to a party to the conflict. The government’s policy is again placing UK service personnel at risk of prosecution, including RAF liaison officers stationed in command and control centres in Saudi Arabia. Rumoured techniques such as walking out of the room whenever a sensitive civilian target is discussed may not be enough for officers to escape responsibility for aiding and abetting a war crime.

In Iraq and Syria, as well as Yemen, the UK government has adopted a strategy of pursuing military objectives “by, with or through” partner forces. While such a strategy may limit the military exposure of UK forces, it should not limit the UK’s liability for aiding devastating violations against civilians.

Mark Lattimer

Executive director, Ceasefire Centre for Civilian Rights

• The ruling from the court of appeal (UK arms exports to Saudi Arabia ruled illegal over risk to Yemenis, 21 June) is to be welcomed. It may interest readers that in February this year the foreign secretary, Jeremy Hunt, one of the contenders for the Tory party leadership and thus to be prime minister, criticised his German counterpart for halting arms sales to Saudia Arabia. “I am very concerned about the impact of the German government’s decision on the British and European defence industry,” he wrote in a letter seen by Der Spiegel magazine (Jeremy Hunt urges Germany to rethink Saudi arms sales ban, theguardian.com, 20 February).

So not only did Jeremy Hunt want to continue UK arms sales to Saudi Arabia, but even more despicably he wanted to dissuade other countries from halting any sales.

Rae Street

Littleborough, Lancashire

• The news from the court of appeal about arms exports to Saudi Arabia should contribute to the celebration of Jamal Khashoggi’s life that your editorial recommends (Riyadh and its friends cannot draw a veil over Jamal Khashoggi’s death, 20 June). The court found that the government had failed to properly assess whether there have been breaches of international humanitarian law. The arms sales – used to bomb schools, hospitals, weddings, and funerals – are not only immoral but illegal.

The government is likely to resist the ruling; a fitting memorial to Jamal Khashoggi’s life would be to ensure this judgment continues to be upheld and even used as a precedent to stop US arms sales to Saudi Arabia.

David Murray

Wallington, London

• With this week’s ruling on arms sales to Saudi Arabia, you might want to again look into the role that RAF Valley on Anglesey has played in training Saudi pilots to drop bombs on the Yemeni people, as mentioned in the Observer some months ago. It is one thing training “our boys” (as I have often seen them called) to fly planes, but quite another to willingly help in the starvation and slaughter of defenceless people in faraway places.

Jeff Teasdale

Macclesfield, Cheshire

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