BRITAIN/Jordan link:In recent years it has become something of a riddle. How did Jordan - the Arab country many considered relatively quiet, stable and modernising; the one some journalists liked to dismiss as the Hashemite Kingdom of Boredom - give rise to a generation of radical Muslim extremists?
Abu Musab Al Zarqawi, considered the brutal mastermind of the Iraq insurgency until his death in a US air strike last year, was Jordanian. Abu Qatada, a radical cleric currently in jail in Britain, is Jordanian. Earlier this year an appeal board heard Qatada had "long-established connections with Osama bin Laden and al-Qaeda" and that he "held sway over extremists".
Also from Jordan is Zarqawi's spiritual mentor, Muhammed Al Maqdisi. Relatively little known in the West, Maqdisi's reputation as scholar and ideologue is unparalleled in contemporary jihadist circles. One US study described Maqdisi as "the most influential living jihadi theorist".
Going back even further in jihadi lore, Abdullah Azzam, Osama Bin Laden's one-time mentor and leader of the Afghan jihad against the Soviets, based himself in Jordan following the 1967 war.
But apart from such high-profile figures, the tiny desert kingdom is also home to many "footsoldiers" who subscribe to jihadi ideology and have acted on it - fighting in Afghanistan, Chechnya, Bosnia and, most recently, over the border in Iraq.
Sometimes they brought the fight back home - Jordan has been targeted several times by homegrown militants, its close ties with the US and friendly relations with Israel often resting uneasily with a population that is more than 70 per cent Palestinian.
In 2005, after years of failed attempts, Zarqawi orchestrated a triple suicide bombing attack in Jordan's capital Amman, killing 60 people.
The news that one of those arrested in connection with the attempted car bombings in London and Glasgow is a young Jordanian may signal that Jordan - and indeed the Middle East's - jihadi problem is reaching for the first time into western Europe. In a significant departure from previous plots and attacks in Britain, most of which have tended to hinge on a strong south Asia connection, those arrested over last week's foiled attacks are predominantly Arab. Another of the men detained is understood to be an Iraqi doctor.
Police said Mohammed Jamil Abdelkader Asha, the 27-year-old doctor arrested with a woman believed to be his wife on a motorway in Cheshire last weekend, was of Palestinian origin and carried a Jordanian passport.
After qualifying from the University of Jordan, Asha began practising in Britain in 2005, according to the General Medical Council. A GMC spokeswoman said he held a provisional limited registration enabling him to work in the NHS under supervision. Most recently he worked at the North Staffordshire hospital in Stoke-on-Trent.
Before moving to Staffordshire last year, where he rented a house in a cul-de-sac in Newcastle-under-Lyme, he had lived and worked in Shropshire.
Asha's father, Jamil Abdelkader Asha, denies his son had any part in the plot. "My son is incapable of such acts," he told reporters in Amman, calling on Jordan's King Abdullah to intervene on behalf of his son. "Not all Arabs are terrorists," he said.
Asha's brother Ahmed said his sibling "is not a Muslim extremist, and he's not a fanatic". The family has described Asha as serious and a bit of a loner. They said he is a devout Muslim. His wife, Marwah, is a university-trained lab technician and they have an 18-month-old son.
Some reports suggest Asha posted messages on several Muslim web forums commenting on the Israeli-Palestinian conflict and criticising the Danish cartoons lampooning Muhammad.
Some will be shocked that a young doctor, far from the stereotypical image of the terrorist, may have been involved in a plan to cause mass casualties. But Jordan, along with many other Muslim countries, has seen some of its brightest and best drawn to the jihadi strain of radical Islamic ideology.
For instance, the man believed to have carried out the deadliest suicide bombing of the Iraq war, Ra'ed Al Banna, had trained as a lawyer, interned with the UN and spent some time living and working in the US.
A majority of Jordan's jihadists describe themselves as Salafi-jihadis, melding jihadi ideology with a rigid, austere interpretation of Islam. This strain of jihadi thought has proved highly appealing to young, disillusioned Muslims. It remains to be seen whether it drove this plot.