Look south as you arrive at Poplar station on London’s Docklands Light Railway and you can’t miss the skyscrapers of Bank of America Corp., Credit Suisse Group AG and HSBC Holdings Plc. Walk north and you’re in another world.

The Will Crooks housing project in this east London district was splashed all over the newspapers at the start of August, when a black flag with white Arabic writing, similar to those flown by the Islamic State jihadist group, was raised over its gates.

The execution of U.S. journalist James Foley by someone with a British accent has sparked soul-searching in the U.K. as to how and why the country has become an exporter of extremists to the Middle East. Prime Minister David Cameron vowed to redouble efforts to stop radicalized Britons traveling to Iraq and Syria to “take part in extremism and violence.”

“The fundamental problem is as long as there’s a conflict, there’s somewhere for people to go,” Raffaello Pantuchi, a counter-terrorism expert at the Royal United Services Institute, a London-based defense and security think tank, said in an interview. “So the supply side of fighters will continue.”

In the 2011 census, the Tower Hamlets borough of about 250,000 people that covers the Poplar area was the only one in the U.K. where more people identified themselves as Muslim than Christian. The Will Crooks estate, a small set of five-story blocks, is typical for the area in being home to many people of Bangladeshi origin. A sign for the local children’s play center is written in English and, underneath, Bengali.

Two Worlds

Population statistics for Poplar don’t give the whole picture, as they also draw in data from the far wealthier neighboring district of Limehouse, home to Canary Wharf and City commuters. Still, 44 percent of those in the area weren’t born in the U.K.; in 20 percent of households, no one has English as their first language; 57 percent of people are non-white; unemployment claims are twice the national average.

Across a divided highway, about 500 yards (460 meters) to the south, the Canary Wharf business district houses shops where bankers can buy 360-pound ($600) cuff links from Mont Blanc and 300-pound lingerie “playsuits” from Myla.

In Poplar, most of the women wear the hijab, the Muslim veil that cover the head and chest, and some wear the niqab, covering everything but the eyes.

Social-Media Draw

When the prime minister broke off his vacation last week to return to London and discuss Foley’s murder, he pushed ministers on what’s being done to stop the U.K. from becoming an exporter of jihadist violence. Between 400 and 500 Britons are believed to be fighting in Syria and Iraq, according to a government official.

“A mixture of things are drawing them there,” Alexander Hitchens, head of research at the International Centre for the Study of Radicalisation and Political Violence at London University’s King’s College, said in an interview. “The social- media element has helped seduce young men to the conflict. That and the face-to-face group interaction -- you find groups of guys going together.”

Also of concern to the government are the 250 Britons estimated to have returned from the Middle East with training and experience of combat, according to the official, who asked not to be identified discussing security matters.

Those returnees are being investigated by police and MI5, the British domestic intelligence agency. This year, 23 passports have been confiscated to stop individuals from traveling and 69 people arrested for incidents related to Iraq- Syria terrorism, according to the government.

British Betrayal

Britain’s intelligence agencies have identified Foley’s killer, the Sunday Times reported yesterday, citing government sources it didn’t name. The sources gave no details of the perpetrator’s identity, the London-based newspaper said.

Foley’s killing by a Briton is a betrayal of “everything British people stand for,” Foreign Secretary Philip Hammond wrote in the Sunday Times. “It is horrifying to think that the perpetrator of this heinous act could have been brought up in Britain.”

The U.K. plans changes to the law that mean naturalized Britons who are fighting overseas can be stripped of their citizenship and excluded, Home Secretary Theresa May wrote in an op-ed in the Daily Telegraph Aug. 23, saying the U.K. “will be engaged in this struggle for many years, probably decades.”

Muslims Targeted

The government is trying a range of tactics aimed at halting radicalization, including support for local campaigns aimed at rebutting extremist propaganda and funding a specialist police unit to tackle Internet content that promotes terrorism. That includes “looking at ways of harnessing social media in the same way recruiters have” to deter potential extremists, said Hitchens of ICSR.

Erin Marie Saltman, senior researcher at the Quilliam Foundation, a London-based counter-extremism research group, says that the issue facing the government is how to stop radicalization without alienating the wider Muslim community.

“Since 2011, the U.K. government has been discussing putting forward a counter-extremism strategy, and we haven’t really seen the introduction of clear measures,” she said in a phone interview. “Many people feel it targets the Muslim community especially, so there’s an element of unrest that it’s targeting a minority.”

Cleaver Attack

On a sunny day last week on the Will Crooks estate, the only thing hanging from windows was washing, as a small girl tried to maneuver a pink scooter over a play area in the midst of the blocks.

There were flags on display elsewhere in the area, but they were the cross of St. George -- a symbol either of support for the England soccer team or for some of the racist groups that have attacked Muslim immigrants.

Abdul Mumin, 43, the secretary of Poplar Central Mosque, was keen to reject links between Islam and the beheading of Foley or the murder of a British soldier, Lee Rigby, outside a barracks in southeast London by two men in their 20s who converted to Islam.

Michael Adebolajo was sentenced to life in prison and Michael Adebowale was jailed for 45 years in February for the killing on a May afternoon last year. Prosecutors told the court they ran over Rigby, then got out of their car and almost decapitated the unconscious soldier with knives and cleavers.

Adebolajo said during the trial that he considered himself a “brother” of the terror group al-Qaeda and didn’t regret “obeying the command of Allah” in the attack.

‘Something Wrong’

Such actions were not connected with a deep knowledge of the religion, Mumin said. According to West Midlands Police, the killers ordered a copy of “The Koran for Dummies” before the attack.

“These people who do these things, we don’t accept it,” Mumin said. “There’s something wrong in their head. This is not Islam.”

There were groups of young Asian men on Poplar High Street, under the watchful eye of a white policeman, but most laughingly said they didn’t want to talk about Syria or radical Islam. They were more concerned to enroll at the local college, which offers diplomas in subjects including childcare and women’s hairdressing and a range of courses for people whose main language isn’t English.

Abdul Alim, 18, was sitting in the park waiting to join the line to sign up for a business-studies course. Did he understand why some of his peers felt the draw to fight in Syria?

“No,” he said, shrugging, and looked up at the Barclays skyscraper a few minutes’ walk away. “I want to be a banker.”