A legal - and potentially lethal - Somalian drug and cafe culture taking root in British cities may may be the next battleground in Britain's fight against terrorism, experts have claimed.
Khat is a green-leafed shrub which when chewed and mixed with saliva produces a mild amphetamine high. It has long been used in Yemen, Somalia and other African countries but is now widely banned in the West, including the Netherlands, generally known for its liberal drugs policy.
In the UK, however, khat is legal, and it is widely available. It costs about £4 to buy a bundle of the stringy green plant wrapped in banana leaves, and is available from supermarkets located in the Somalian communities found in London, Bristol, Birmingham and other cities.
More than 100,000 people of Somali origin live in the UK, according to most estimates. A 2005 Home Office report found more than half of Somali men in the UK used khat, and that almost 80% used more than they did in Somalia.
According to people who use it, khat makes users feel energetic, chatty and confident. In 2008 a (predictably effusive) reporter for Vice magazine took khat and wrote later that after about 10 hours of constant chewing he "felt certain that I could chat up any chick and win any argument. Instead of pretending to throw a punch as a joke, I got all hyper and threw a chair".
Like most drugs khat has significant medical side effects. According to drugs advice website Frank, its use can cause insomnia, delusions, high blood pressure, anxiety and even mouth cancer. Most studies say that khat is also addictive, and can produce withdrawal symptoms.
But in the context of the Somalian civil war, critics say, khat isn't just harmful - it's deadly.
Every aspect of the drug, from its production and export to the cafes where it is sold and chewed, has been linked to the al-Shabaab terrorist group which on Wednesday carried out another deadly suicide bombing in Somalia.
The khat cafes ('mafrishes') where the drug is usually taken are often almost impossible to find unless you know where to look, and are hidden behind locked shop shutters or unmarked doors.
Critics say they are increasingly acting as recruiting stations for the al-Shabaab terrorist network, and many mafrishes are reportedly hostile to outsiders. The Huffington Post UK was advised not to even attempt to enter.
Abukar Awale, a Somalian in the UK who is campaigning to ban khat, says that the cafes snare young, vulnerable and usually unemployed Somali men, for whom the legal high leads to a circle of "pain and suffering". And as the most prominent Somalian critic of khat publicly calling for it to be banned in Britain, Awale says he has been threatened by those involved in its sale.
A former addict himself, he told the Huffington Post that as a user "you wake up at 3 in the afternoon, you're awake all night chewing it, and you go back to bed in the morning and in order for you to function, to feel that your confidence is up, you have to chew again."
Young users at the mafrishes can fall into a life of crime, Awale argues ("soon enough they're selling minor drugs just to support the habit") and while on khat are more vulnerable to radicalisation. He points to two British citizens who were recently arrested in Kenya suspected of working for the terrorist group as an example of the type of people being targeted by fundamentalists. Two other British Somalis, 18 and 20 years old, have also been reported missing in recent weeks and are suspected to be in Somalia fighting for al-Shabaab.
"There is paranoia that grows inside them," Awale said. "They think everyone is out to get them… They develop a lot of anger and hate towards police and the British public"
"That's exactly the people that al-Shabaab are targeting now."
Even outside the mafrish the wider social consequences of khat are hugely damaging says Dalmar Osman, who is the director of the Somali Development Group, which works with young Somalis in Bristol.
"The majority of the Somali male figures who chew it don't have a lot to say in the family household [because they become disengaged] which then for the young people makes a real impact," he said. "They are losing their male role model, and that plays a role in radicalisation and extremism, especially in Somalia itself."
Osman is holding a four-day event in London this April to educate young Somalis on the dangers of khat, and to inspire them to break the deadly cycle of unemployment and depression.
"It's not a cultural issue," he said, of the prospect of khat being banned. "If a young person starts chewing, which is not uncommon, it puts you a position where anything wrong becomes right in your eyes and it becomes easy for them to go in a bad direction, or a criminal direction."
The production and sale of khat is also thought to fund the terrorist networks attempting to prey on British youth.
The plant is imported, usually from Kenya, four times a week via Heathrow, with less frequent imports from Ethiopia and Yemen. In 2010 HMRC said that more than 57 tonnes of khat was imported - on which it collected £2.9m in VAT.
Sources also told the Huffington Post UK that senior al-Shabaab leaders were formerly involved in illegally exporting khat from the UK to the countries where it is banned and were running some of the cafes themselves. The HMRC also admits that a "small percentage" of the khat imported legally is later exported to countries where it is banned - making huge profits for the criminals linked to terrorist networks who sell it.
A report by the Royal United Services Institute said western security and intelligence agencies face new challenges "as jihadism evolves and disperses into territories of ungoverned, or loosely governed, space across large stretches of the African continent".
"Most significant is the potential for radicalisation and then mobilisation of a new subset of British youths," wrote the author of the report, Tina Soria.
She told the Huffington Post UK that British Somali extremists can be more valuable to al-Shabaab than locals because they are more likely to agree to carry out suicide bombings. Several British and American citizens have been killed in Somali attempting to carry out suicide bombings.
"The issue of that community not being integrated or alienated in some way is the perfect profile of a possible terrorist or extremist. But economic and social factors play a major role too," she said.
The threat of a British individual inspired by al-Shabaab committing an attack in the UK is real, she added, even if it doesn't come as a direct order from the group's leaders in Africa.
Amid all of this criticism there are increasing calls from politicians and campaigners to ban the drug for good. A previous government study in 2005 said that the drug should not be controlled, but following further research in 2011 it decided to take another look. The Advisory Council for the Misuse of Drugs is currently conducting a study based on which the government will decide if it should be taken off the shelves.
But some argue that banning khat would just embolden the same terrorist networks currently suspected of benefiting from its legal sale.
Axel Klein, an expert witness for the ACMD's 2005 report, recently told the BBC that banning khat could create "an organised crime syndicate to start-up from nowhere".
And in the opinion of many Somalis, khat cafe culture is just a healthy part of a normal social life. Khat may be addictive, but among those who use it many live otherwise normal lives.
When a group of councillors from Brent went to visit a local mafrish earlier this year they described a friendly and positive atmosphere, where "the communal nature of chewing khat was obvious – unlike in a pub, where people tend to talk to their friends, everyone in the room was sitting in a circle talking". Most of the men there visited after work, they said, and mainly chatted about sports, Somali politics and their everyday lives.
Despite this experience Brent council decided to impose a "voluntary agreement" with retailers to restrict its sale to under-18s and to increase awareness about its health risks.
Somalis in the UK remain divided on the issue - and on whether adding yet another substance to the growing list of illegal highs will make the difference to a community blighted by unemployment, poverty and violence.
“I think no need to intervene," one Somali khat user said in a recent study on attitudes to its use. "The government is not banning alcohol which is more harmful. Khat users are not intoxicated and can work and drive a car without a problem. So why not ban alcohol first?”
And as a recent Middlesex University study pointed out, when dealing with Somalia and its brutal recent history of violence, civil war, forced migration and poverty, isolating khat as the cause of all its ills is likely to prove shortsighted.