Amid concern about civilian casualties in Yemen, the United States is cutting back on arms sales to Saudi Arabia – at a time when the Britain, the kingdom's other main supplier, is trying to increase them.

The US has decided not to go ahead with a $350 million sale of 16,000 guidance systems which turn "dumb" bombs into "precision" bombs, the New York Times reports. The guidance systems are supplied by an American company, Raytheon, but at least some of them are manufactured in Britain.

An Obama administration official told Reuters the decision was "a direct reflection of the concerns that we have about Saudi strikes that have resulted in civilian casualties." 

In theory, precision weapons ought to lower the risk of civilian casualties but the Saudis have been misusing them through a mixture of incompetence, indiscipline and flawed intelligence. 

During a previous Saudi bombing campaign in Yemen, in 2009-2010, the Americans complained about attacks on civilian targets and presented them with a satellite image of a Yemeni clinic that had been hit. The Saudis responded by asking the Americans for more accurate weapons.

Since then, though, American supplies of precision weapons have made little or no difference. During the current Yemen war the Saudis have not only failed to safeguard civilians in their targeting but on numerous occasions have also targeted civilians directly.

For the US, the crunch came in October when the Saudis bombed a large funeral gathering, killing at least 140 mourners and injuring more than 500. An official report later blamed false intelligence and said the attack had been launched without proper approval from commanders.

Meanwhile, the British government is in a state of denial. Last month it rejected calls from two parliamentary committees for a suspension of arms sales to Saudi Arabia until a UN investigation had been conducted into attacks on civilians.

The British government has a legal obligation not to allow exports of arms if they "might be used in commission of a serious breach of international humanitarian law". Despite overwhelming evidence of war crimes in Yemen the British government continues to insist this test has not been met.

The funeral attack in Yemen last October was of a type known as "double tap", where a second bomb strikes as rescuers move in after the first bomb. Britain's foreign secretary, Boris Johnson, has previously described double-tap bombing as "unquestionably a war crime" – but he was referring to Russian double-tap attacks in Syria and not Saudi  double-tap attacks in Yemen. 

Britain's determination to keep on arming the Saudis is partly due to the lucrative nature of the sales and the British establishment's historical infatuation with the Gulf's autocratic rulers.

Over the last few months dreams of expanding trade in the Gulf have also become part of the government's Brexit fantasyland where steady markets in Europe will be abandoned in favour of markets subject to the vagaries of Middle East politics