Airstrikes that hit the wrong target have always been justified or denied by the perpetrators with a rich blend of hypocrisy and lies. It was interesting to see this tradition of deliberate mendacity being not only maintained, but outdone in Syria over the last week. The US was seeking to explain how it had come to kill at least 62 Syrian soldiers fighting Isis in the besieged government-held city of Deir Ezzor a week ago and the Russians evading responsibility for an air attack on a UN aid convoy killing 20 people outside Aleppo five days later.

The explanation of US military officials was splendidly ingenious. As dutifully retailed by CNN, they said they believed a likely scenario was that the personnel hit were prisoners of the regime, perhaps military personnel being detained, although that is not certain.

The initial signs indicated that they were dressed in civilian clothing. They may not have had the typical weapons of a Syrian military unit but rather trucks with weapons mounted on top of them. It is also not known if they were deliberately placed there to potentially deceive the coalition.

UN talks on Syria end without breakthrough

For students of war propaganda this is a wonderful piece of obfuscation. No evidence is produced for “the likely scenario” in which supposition is heaped on supposition. Its purpose is instead to mask, or throw in doubt over, the obvious fact that someone had committed a blunder and ordered an attack on a long established Syrian Army position near Deir Ezzor airport. This sort of smoke screen is not designed to last very long, but to blunt criticism during the first crucial few days when the story is still at the top of the news agenda. Then a few weeks or even months down the road, there can be a grudging admission of the truth, or part of it, when it will barely get a mention at the end of newscasts or be relegated to page 24 of the newspapers. An old PR adage says that the best way for the perpetrator of some disaster to limit the damage to himself or herself is to “first say no story and then say old story.” It still works.

The Russian explanation of the attack on the UN aid convoy on 19 September is also well worth studying as an example of the propagandist’s art. It is important to make your explanation detailed and interesting because it will be competing with a reality which, in the nature of war, will be murky and confusing. The Russian news agency Tass quoted a senior Russian official as saying that “analysis of video records from drones of yesterday’s movement of the humanitarian convoy across Aleppo territories controlled by militants has revealed new details. It is clearly seen in the video that a terrorists’ pickup truck with a towed large-calibre mortar is moving along with the convoy."

This was good stuff. Suggesting that there was an understandable reason to imagine they were attacking a legitimate target – though it had to be admitted that “the large calibre mortar” had somehow disappeared by the time of the attack. But the Russians made the mistake of producing too many exculpatory stories at the same time, claiming there were no Russian or Syrian planes in the area – in which case why suggest the legitimate target scenario? Other Russian explanations were that there had been no attack at all and, if there had been, it had been carried out by jihadis and, in any case, all the damage was done from the ground and not from the air.

The crucial point is never to leave a vacuum of information when a story is at the top of the news agenda because that vacuum will be filled by your enemies (if it has not got wide media attention it may be better to ignore it because a rebuttal may serve only to give the story legs). It does not matter if what you are spouting is nonsense because it only has to hold up for two or three days and probably less (the UN aid convoy attack was swiftly overtaken as a news story by the riots in Charlotte, North Carolina). An advantage for the propagandist is that it is easy to make up a lie, but it can take much more time and effort to convincingly refute it.

Turkey's two million Syrian refugees Show all 11 1 /11 Turkey's two million Syrian refugees Turkey's two million Syrian refugees There are already over 2.5 million Syrian refugees in Turkey, but their current camps can only hold 200,000 people ADEM ALTAN/AFP/Getty Images Turkey's two million Syrian refugees Turkish citizens protest a new deal, also criticised by human rights activists, which will see refugees who arrived in Greece after March 20 be sent back to Turkey AP Photo/Emre Tazegu Turkey's two million Syrian refugees An estimated 80% of Syrian refugee children already in Turkey are unable to attend school BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Refugee children beg for water near the Turkey-Syria border. Turkey has been accused of illegally deporting asylum-seekers back to Syria BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees In Turkey, no-one from outside Europe is legally recognised as a refugee, meaning the 2016 deportations may not meet international legal standards for protecting vulnerable people BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees A refugee child cries as she is searched by police at the Syria-Turkey border, where 16 refugees (including three children) have been shot dead in the last four months BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Many refugees are living rough on the streets of cities such as Istanbul or Ankara (pictured) ADEM ALTAN/AFP/Getty Images Turkey's two million Syrian refugees Turkish soldiers use water cannon on Syrian refugees BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees Syrian refugees shelter from rain in the streets of Istanbul BULENT KILIC/AFP/Getty Images Turkey's two million Syrian refugees A derelict building housing Syrian refugees in Istanbul Carl Court/Getty Images Turkey's two million Syrian refugees Turkey houses around half of all the refugees who have currently fled Syria Carl Court/Getty Images

The truth is that air attacks fail to hit the right target regularly, though not often with such diplomatically disastrous consequences as last week. Air forces emphasise that with smart bombs they can hit targets with far more accuracy than ever before, but they seldom stress that the targeting is based on intelligence which may be flawed or misinterpreted. The misinterpretation may take place far away in some operations centre or it may be some partisan local source peering through binoculars.

Most intelligence comes from local ground forces. The RAF says that the reason that it has only launched 65 airstrikes in Syria over the last nine months compared to 550 in Iraq is that it lacks partners on the ground in Syria while in Iraq it has the Iraqi Army and the Kurdish Peshmerga.

Bombing blunders have a certain amount in common in all recent wars. In 1991, I went to the Amariyah shelter in Baghdad where sometime earlier the US had dropped two smart bombs that had incinerated 400 people, mostly women and children. The US had supposed it was a command centre based on radio signals and local informants. The reliability of these spies could be judged by several disastrous attempts, based on their information, to kill Saddam Hussein and his senior lieutenants who turned out to be nowhere near at the time.

In 2009 I reported on an airstrike in three villages in Farah province in south west Afghanistan, which had killed 147 villagers. It had started when there was a fight between local Afghan police and the Taliban in which the police had come off the worst. Three of their vehicles had been destroyed. Because they were frightened – and perhaps as an act of vengeance – the police (though they must have got a US Special Forces officer to sign off on this) had called in airstrikes that had destroyed the mud brick walls of the compounds and left craters 20 feet deep. The first US military explanation of what had happened, repeated by US Secretary of Defence Robert Gates, was that the Taliban themselves were responsible.