The 'Enemy' Within

In light of the Glasgow and London car bombs CNN aired a special with Christiane Amanpour called the Enemy Within. The documentary was about the spreading ideology of extremism amongst the Muslim youth. The documentary took on two schools of thought with Islam in the UK. The extremist side and the more moderate side. A failed attempt to integrate immigrants or mix the proverbial melting pot can probably be cited as a reason for the resurgence of extremist points of view.

The United States probably doesn't see the threat of home grown terrorists for a couple of reasons

Difference between USA and Britain in immigration policy:
Between the 50s and 70s a large number of South Asian Immigrants came to live in Britain due to their previous status as 'subjects of the empire'.

1.6 million Muslims in Great Britain (Total population: 60 million)
2 million Muslims in the US (Total Population: 300 million)

Immigration policy in the US and Canada is regulated such that individuals from Asia and Europe must be skilled workers, investors or seeking amnesty.

South Asian and North African 'Ghettos'
France: The French pride themselves of being the most sophisticated liberal thinkers in the world. However the rise of North African ghettos and separation of blue-collar immigrants with the rest of the population and the fact that the government neglected them (in terms of municipal services) clearly show hypocrisy

Britain: The same phenomenon can be seen in Great Britain with large congregations of South Asians living in homogeneous pockets in city centers like Birmingham. These backfire on the majority as poverty leads to centers of dissent.

However I want to pose this question: Is segregation a natural choice of blue-collar immigrants or is it stealthily forced upon them by the government?