In Kate Atkinson’s dazzling 2015 novel, A God in Ruins, about war and the shadow it casts, there is an exchange between the main character, an RAF pilot who is involved in the terrible aerial bombardment of Hamburg in 1943, and his sister, in which she probes how heavy the deaths of civilians weigh on his conscience. She asks: “The civilian population considered to be a legitimate target – innocent people. It doesn’t make you feel ... uncomfortable?” His reply is loaded with Old Testament spite and vengeance. “We don’t target civilians! Can you devise a war where no one is killed? We have to destroy their industry, their economy, if we’re to win. Their housing, too, if necessary. I’m doing – we’re doing – what’s been asked of us to defend our country, to defend freedom. We’re waging war against a deadly foe and we’re risking our lives every time we fly.” As the novel unfolds, history teaches the main character that Hamburg was no turning point, but rather a staging post in the violence that led to Hiroshima. Ultimately he is broken by this knowledge, a “god in ruins” to borrow Atkinson’s resonant phrase.

Britain still fights, but thankfully not on the appalling scale of the world wars of the last century. Last week the defence secretary admitted for the first time in the four years of anti-Isis operations in Iraq and Syria that UK forces caused civilian harm. Ministers said a missile fired from a drone this March “unintentionally killed” a civilian in eastern Syria. The admission came a day after the BBC reported that British forces had likely caused civilian deaths “on several occasions” in the tough and brutal battle to take the Iraqi city of Mosul. While the Ministry of Defence’s concession of a single civilian fatality is a welcome step towards greater accountability, it is also a tiny one. There is an astonishing disparity between official statistics and the findings of researchers like those at Airwars, a not-for-profit organisation that tracks military action in combat zones, which estimates that 6,000 civilian deaths have been caused by coalition attacks since operations began. This may be because the forces – US, French, British and Australian – investigate only those attacks they deem necessary. This is problematic because the military tends to emphasise the surgical nature of airstrikes or the “precision” with which they practise warfare in cities. This means, like the main character in Ms Atkinson’s novel, the armed forces appear to wage wars without a true understanding of the costs, only to discover later that civilians caught up in conflict tragically understand them all too well.

Coalition forces are fighting a brutal enemy that, unlike them, has no concerns about killing civilians. But western militaries have a moral responsibility to take extraordinary care that innocent lives are not lost. This is harder when nations like Britain are unable to confess to the scale of our own mistakes. US experts say such a lacuna raises serious concerns about compliance with the laws of war. Undercounting civilian casualties after airstrikes may affect the pre-strike assessment of expected civilian casualties. If allowed to continue unchallenged, military operations might fail to take adequate precautions to avoid non-combatant deaths or to ensure bombing raids are proportionate to the threat posed. These are live concerns: campaigners have won the right to appeal against a decision to allow UK arms sales to Saudi Arabia because they “might be used in the commission of a serious violation of international humanitarian law”. Britain ought to shrink the credibility gap in accounting for civilian casualties – and properly investigate claims of harm.