IS using suicide attacks on 'industrial scale'
Almost 300 Islamic State (IS) militants have killed themselves in suicide attacks in Mosul since Iraqi forces started an offensive to recapture the city in October, according to the jihadist group's propaganda. Charlie Winter, who has published a study for the International Centre for Counter-terrorism in The Hague, investigated the tactic.
When Manchester-born suicide bomber Jamal al-Harith drove an explosives-packed SUV into Iraqi forces at an army base in Tal Gaysum earlier this month, he did so as part of a strategy that has seen suicide attacks carried out at an unprecedented rate.
At the end of January, IS published a video eulogising one of the hundreds of attackers deployed recently, a young Iraqi boy who was filmed inside his vehicle-borne bomb before setting out on what the group calls a "martyrdom operation".
In the film, the boy delivers a scripted speech to the camera.
This exploitation of children is one particularly ugly facet of IS's approach towards suicide attacks, which has seen it carry out more than any other insurgent or terrorist group, even al-Qaeda.
Seven months ago, I began carefully going through IS official media hoping to use it as a window into the minds of its military strategists.
Given that every single one of the photographs and operation claims I came across was propaganda, I discounted much of what was said, looking only for descriptive details such as dates, locations, names, and so on which were unlikely to have been exaggerated.
Of the 15,014 images and reports I collected, more than 1,000 made reference to suicide operations in 2016.
No fewer than 923 fighters were individually commemorated as "siham al-khilafa", or "arrows of the caliphate".
IS has industrialised the use of suicide attacks - they are its guided human missiles, dispatched in groups to hit armoured vehicles, break through fortifications, or derail offensive operations.
It has special schools and indoctrination centres where suicide operations are promoted as the "quickest and easiest path to paradise".
The suicide bomb threat - Chris Vallance, Radio 4 PM
When a car bomb detonates little is left.
BBC cameraman Marek Polaszewski remembers seeing an engine block still steaming 20m (66ft) away from the site of one attack, the only recognisable remaining piece of the vehicle or its driver.
Iraqi Kurdish Peshmerga commander Lt-Col Shorsh Salahidin was fighting in Kobane, Syria, when their positions were attacked by car and truck bombs.
"The blast is massive," he told me. "It is like being only half conscious of what is happening in front of your eyes."
Although he was not physically harmed in the attack, Col Salahidin "we felt wounded, mentally wounded".
Joe, a British man who fought with Kurdish forces in Syria, has seen the insides of captured vehicles.
"They rip out everything" to make room for explosives and fill the vehicles with bags of "metal objects, nuts, bolts", he says.
Defenders, he said, could be hit by shrapnel kilometres away.
"It doesn't soften us" he said, but it makes attackers wary. "It slows us down."
IS suicide fighters died in vehicle bombs 70% of the time, according to my research.
Occasionally, they also killed themselves by detonating concealed explosive belts and vests, or went into battle intending to die when they were deployed as "inghimas" fighters - IS's suicidal equivalent of special ops units.
While it tends to be cases of foreign suicide bombers like Jamal al-Harith, a former Guantanamo Bay inmate, that generate headlines, just under three-quarters of the men and boys that killed themselves for IS in 2016 were from either Syria or Iraq.
The rest came from 32 states all over the world, from West Europe and North Africa to Central and South-East Asia.
In 2016, according to IS propaganda, 84% of the group's suicide attacks were geared towards hitting enemy targets - fighters, vehicles and barracks.
But as it lost more and more territory towards the end of the year there was a shift in approach and an unmistakeable increase in suicide operations that targeted civilians.
Perhaps IS hoped to buoy flagging morale among its supporters.
For the group, terrorist attacks against non-combatants generate momentum in the same way that taking over territory does.
What IS leaders call a "decisive weapon" is increasingly a tactic of last resort, more like the kamikazes of Imperial Japan during World War Two than al-Qaeda suicide bombers in the 2000s.
However, it is also a strategy that requires a constant supply of human lives.
Charlie Winter is an associate fellow at ICCT, based at London's International Centre for the Study of Radicalisation and Political Violence.