IS conflict: Counting the civilian cost of US-led air strikes
At 00:30 on 7 December, Abu Khalil and his family were sound asleep at their home in the north-eastern Syrian village of al-Khan.
They were woken by the sound of a huge explosion.
The house shook. The windows shattered. There was shrapnel in the walls.
Abu Khalil ran out and saw that his neighbour's house had collapsed. The neighbour was frantic and shouted to Abu Khalil to help him find his six-month-old baby.
"I could hear people calling from underneath the rubble," said Abu Khalil. "My neighbour's mother was crying out. She's 70."
It was an air strike, but not by the regime. The villagers say it was the US-led coalition against the jihadist group Islamic State (IS), and that some 47 civilians were killed, half of them children.
If that is true, this was one of the worst accidental bombings of the campaign against IS.
We spoke to Abu Khalil by phone. He is an Arab man in his 30s but did not want to be further identified. He said he was afraid of reprisals by the Syrian People's Protection Units (YPG), which controls much of Hassakeh province and is a key ally of the US-led coalition.
He told us the casualties were so high in the attack on al-Khan because the house hit in the initial strike - by a rocket - was packed with people who had fled other villages. The village was also strafed from the air, he said.
Abu Khalil managed to drag his neighbour's mother from the wreckage of the house, along with a boy and his mother. They were OK - at first.
He described the scene as others in the village came running to help: "My mother and my aunt were both digging through the rubble with me. But while we did this, a helicopter came overhead. It fired. They had machine-guns with explosive bullets. I was hit. I still have the shrapnel in my body.
"I fell into the hole made by the air strike. That was what saved me. The helicopter circled round again and fired a second time. My mother and aunt were killed. The woman and her son who I'd rescued were killed. Everyone but me was killed."
Abu Khalil said the initial air strike was a rocket or missile fired by an Apache helicopter. It left a 2m-deep hole in the ground.
'It was the Americans'
"Anyone could see the hole until the PKK [Turkish rebel Kurdistan Workers Party] filled it. They don't let anyone go near the place or take pictures.
"It was the Americans. For the past year-and-a-half, the only aircraft that have flown over our area have been American."
When the first, sketchy reports came in about al-Khan in early December, the US military's Central Command (Centcom) said it would investigate.
Centcom now says it has looked at its records and did not attack the village. A spokesman stated, however, that there were air strikes in the area of al-Hawl, a small town a few kilometres away.
Al-Khan is a tiny village. According to Abu Khalil, fewer than 100 people live there. Local activists have looked at a map provided by the US military marking the location of the air strike - they say that is exactly where al-Khan is located.
There was confirmation of an air strike on al-Khan from another important source - the Kurdish forces on the ground.
A web page apparently published by the YPG, states: "Coalition aircraft made several raids on IS targets in al-Khan and finished off many rats."
The page purports to come from Raqqa is Being Slaughtered Silently (RIBSS), a human rights organisation known for its brave opposition to IS. But RSS has told us the page is nothing to do with them.
The whole thing has the whiff of propaganda about it - an exercise in denying there has been any kind of serious incident because that might undermine support for an air campaign.
Abu Khalil told us that the Kurdish militia had filled the hole made by the initial strike and would not let anyone go near it or take pictures.
He accepts that there was an IS presence. But he said: "There were fewer than 10 fighters in the village, including two locals. And they all stayed together at one place."
He said the village did not support them: "People in al-Khan didn't like IS and always avoided talking to them."
The villagers even tried to expel IS, he said. According to one report, there was an altercation that escalated into an exchange of fire - and IS responded by sending reinforcements.
This convoy, it seems, was spotted by the Kurds, who no doubt thought they were seeing a big movement of troops to the frontline - and called in air support.
If all this is correct, the village's opposition to IS resulted in a devastating attack by US aircraft.
There are many things that are unclear about the events in al-Khan. How many IS fighters were there? How many of them were killed? Were they close to the house that was hit?
There are no independent witnesses, but there is testimony from survivors such as Abu Khalil and others.
And while the villagers counted 47 dead, the coalition counted none.
To some, what happened at al-Khan tells you why the US military's own estimate of civilian casualties in the war against IS is simply not credible.
In an 18-month-long campaign, during which coalition aircraft have conducted 7,550 air strikes in Iraq and Syria, the US military so far acknowledges causing the sum total of 22 civilian deaths.
By contrast, an independent monitoring group called Airwars says that at least 846 and as many as 1,166 non-combatants have died in coalition strikes in Syria and neighbouring Iraq.
Of course, IS makes the most of civilian casualties. One of the most effective - and upsetting - IS propaganda videos I have seen is of the aftermath of an air strike on the hospital in the town of Abu Kamal, in eastern Syria. It is professionally shot and edited, in high definition as we have come to expect from the jihadist group.
A trail of blood is shown going up the stairs to the neonatal unit. Inside incubators and other equipment are strewn around. The camera points to the floor to get a close-up of the face of a dead baby. The baby's face is coated in plaster dust and fills the screen.
Battle for public opinion
"This is the work of the Crusader Coalition," the video says.
"They accuse the Islamic State of killing civilians! What do you call this? Destroying a hospital with newborns - this is terrorism, not what the Islamic State does. When the pilot falls into our hands, we will bring down justice upon him!"
Was this the coalition or could it have been an air strike by the Syrian regime, or shelling by one of the armed groups fighting IS?
While there is no record of a coalition air strike on Abu Kamal on the day the hospital was hit - 6 March - a coalition press release does talk about an oil pipeline nearby being bombed.
In one sense, it does not matter. IS claims it was a coalition air strike and uses it as propaganda in the battle for Sunni Muslim public opinion.
While the coalition is extremely cautious about estimating the number of civilians killed, there is no such reticence when it comes to the number of enemy dead - at least 23,000, according to briefings given by officials to US media.
This figure may be exaggerated. The CIA has repeatedly said IS can put 30,000 fighters in the field. Can it really be that they have lost three-quarters of their strength to US bombs? And since the CIA estimate has not wavered, has IS really been able to replace 100% of its losses?
But even if total IS casualties are only half what is claimed, or a quarter, something remarkable is happening. Thousands of the enemy are being killed with, so far, very few coalition casualties. Just a single US death is classed as being caused by hostile action.
It is a vastly uneven contest and one in which, ultimately, the industrial and military might of the US will almost certainly prevail.
IS militants have been steadily losing territory. They may be on the point of abandoning much of Aleppo province, with the latest reports speaking of senior figures leaving the main IS-controlled town there, Manbij.
The seriousness of the situation - even the possibility of defeat - was acknowledged in late December in an audio message purportedly from IS leader Abu Bakr al-Baghdadi.
"If we are victorious then God has promised it to us," he said. "But let us not get bewildered if death, injuries and defeat overcome us because it's God's promise to us as well."
'Muslim against Muslim'
We spoke via Skype to Abu Haider, a defector from IS. First of all, he said, the militants had adapted to the coalition's bombing.
"Air strikes won't affect them. They are well trained, they use walkie-talkies to warn of an attack. They have made shelters."
But, he went on, morale was low among ordinary fighters as the group fell back. "They are frustrated because the entire world is fighting against them," he explained.
There was another reason for poor morale. People were disillusioned - the so-called Islamic State had not lived up to its promise.
A medical student when the protests in Syria began, Abu Haider was very religious, much more so than his family. From the start, he saw the uprising as jihad, not a revolution for democracy. But IS turned Muslim against Muslim.
"We went to the Islamic State because they said they were establishing Sharia and protecting Muslims. But we witnessed something very different," he said.
"They were killing Muslims - from the Free Syrian Army, from al-Nusra Front, from Ahrar al-Sham. This is unacceptable... I joined the Islamic State to fight the regime."
That disillusionment does not mean Abu Haider would take arms and money from the US to fight IS.
"I would never join the coalition led by the US," he said. "I would never choose Americans over Muslims, even if they are IS."
"The Americans are our enemies, although their time hasn't come yet. We are already fighting against the Shia and the Russians."
That declaration illustrates the problem for the US that many of those fighters opposed to IS share the same basic aims.
Abu Haider believes in a scriptural prophecy of a final battle marking the end of days, a prophecy he said was constantly invoked by IS commanders and clerics.
They would tell him that the battle would be at the village of Dabiq in northern Syria, against the "forces of Rome", the "Crusader coalition".
Some IS members will not leave the group but will fight to the last bullet. The death throes of IS could be drawn out - and with it the US coalition's air war.