Officials investigating attack that killed more than 300 people believe the bomber may have been motivated by desire for revenge for a raid in August
The man who killed more than 300 people with a truck bomb in the centre of Mogadishu on Saturday was a former soldier in Somalia’s army whose home town was raided by local troops and US special forces two months ago in a controversial operation in which 10 civilians were killed, officials in Somalia have said.
The death toll from the bombing now stands at more than 300, making it one of the most devastating terrorist attacks anywhere in the world for many years. On Tuesday remains of victims were still being brought out of rubble spread over hundreds of square metres.
Investigators believe the attack on Saturday may in part have been motivated by a desire for revenge for the botched US-led operation in August.
Al-Shabaab has not claimed responsibility for Saturday’s attack but a member of the cell detained by security forces has told interrogators the group was responsible, one security official told the Guardian.
Following the raid, in which three children aged between six and 10 died, local tribal elders called for revenge against the Somali government and its allies.
Not only was the bomber from the specific community targeted by the raid, but the investigation is also uncovering a series of other links to the town where it took place.
Details of the attack are now becoming clearer. Officials say it involved two vehicles – a Toyota Noah minivan and a much larger truck carrying around 350kg of military grade and homemade explosives.
The target for both vehicles was the heavily guarded airport compound in Mogadishu, where the United Nations, most embassies and the headquarters of the 22,000-strong African Union peacekeeping force, Amisom, are based, officials said.
The smaller device was supposed to blast open the heavily defended Medina Gate entrance to the compound to open the way for the bigger bomb, a standard militant tactic.
The minivan was stopped by at a checkpoint several hundred metres short of its target and the driver detained. This bomb later detonated, possibly set off by remote control or by security officials, without causing casualties, two officials told the Guardian.
Officials also said the driver was a veteran militant who had been involved in previous attacks in Mogadishu, including one on the Jazeera hotel in 2012 in which eight people died.
The bigger truck bomb was detonated at a busy crossroads at least a kilometre from the Medina Gate when it reached a checkpoint where security guards became suspicious. The explosion ignited a fuel truck nearby which caused a massive fireball. It has been impossible to identify the type of truck from the wreckage.
Officials said the driver had joined the army in 2010 but defected from his military post to join al-Shabaab around five years later.
The US involvement in Somalia intensified in the later years of the Obama administration but has increased significantly since Donald Trump became president, with greater latitude given to local commanders to order airstrikes or take part in raids.
Critics have argued this risks greater civilian casualties, which, in the tight-knit world of Somalia’s complex clan system, can prompt feuds and revenge attacks.
The raid in August targeted the small town of Bariire, 30 miles (50km) west of Mogadishu, which is a stronghold of al-Shabaab.
Investigators have established that both vehicles used in Saturday’s attack appear to have set out from Bariire, and the owner of the truck used for the bigger bomb was from the town or the surrounding region, officials say. He has been detained.
Investigators are probing the possibility that some individuals manning the checkpoints on the route taken by the bomb vehicles into Mogadishu from the direction of Bariire may have been complicit in the attack.
All those on duty on Saturday have been removed from their posts and put under investigation, apart from those who successfully stopped the smaller vehicle. The personnel who tried to stop the truck bomb near the Kilometre Five checkpoint are all dead.
Bariire is known as an al-Shabaab stronghold which has been a lanchpad for several major attacks on Mogadishu.
The group has been pushed out of major cities but retains control of swaths of countryside in the south and centre of Somalia.
In May a US Navy Seal was killed and two troops wounded in a raid on an al-Shabaab militant compound in Bariire, in what was the first US combat death in the African country since the 1993 “Black Hawk Down” disaster.
The town was recaptured by government troops earlier this year but abandoned in a “tactical withdrawal” last week. Analysts say the retreat left Mogadishu exposed.
The area has also been the site of intensive activity by US drones. Local media reported airstrikes around Bariire on Tuesday.
The links between the attack and Bariire will raise questions about the tactics and strategy of the campaign against al-Shabaab.
“If you go out more aggressively in this kind of environment you risk scoring some serious own goals. The extremists really cranked everything they could out of the botched raid in August. They put out images of the bodies of the kids, published the testimony of supposed witnesses,” said one western counter-terrorist expert with long experience of working with Somali authorities.
A second expert, who works closely with regional security forces in Somalia, described as “very plausible” the possibility that al-Shabaab, which have always exploited clan allegiances, may have played on traditions of exacting vengeance to convince members of the clan to assist al-Shabaab in the bombings.
A recent United Nations study found that in “a majority of cases, state action appears to be the primary factor finally pushing individuals into violent extremism in Africa”.
Of more than 500 former members of militant organisations interviewed for the report, 71% pointed to “government action”, including “killing of a family member or friend” or “arrest of a family member or friend” as the incident that prompted them to join a group.
• This article was amended on 18 October 2017 to clarify the context for the second expert’s view.