After the Islamic extremist terrorist attack on America on Sept. 11, 2001, there were fears of anti-Muslim backlash. But 25 years later, the script has been flipped. 

Ten million or more Muslims have immigrated to the west. 

Today, Muslim figures are mayors of New York and London. But there’s also conflict. Europe is gripped by tensions caused by the rapid demographic change.

A fatal stabbing in Southampton, south of London, last December provided one example of the cultural and political pressure point. 

Bodycam video showed police buying into the killer’s false claim that he’d been racially attacked. Vickrum Digwa – a Sikh and son of an Indian citizen– pretended to be the victim, while officers handcuffed the real victim: college student Henry Nowak, as he bled to death.

There’s been a surge in protests across Europe. And two-thirds of Britons now say the total number of immigrants is too high. Both major parties – Conservatives and Labour – have faced public anger and disappointment over years of broken promises.

Iain Duncan Smith is a Conservative member of Parliament and former party leader.

“We've overcooked migration,” he told Full Measure during an interview at a London park. “We've been far too lax and too easy. 

"So we have to crack down on that. And the only way to have cracked down on it was what I supported, from the word ‘go’m, was to say to those who arrive illegally, ‘You're going on the next aircraft back to somewhere further away than you came from, OK?’ 

"Once they realize the risk at sea and the cost is no longer outweighed by the opportunities, they won't come anymore. That's the way to deal with it, but we have to be hard about it and the government's very weak at the moment and not able to do it.”

But European courts have repeatedly blocked immigration crackdowns, ruling it a violation for the United Kingdom to fly illegal immigrants from Africa and the Mideast to Rwanda for processing.

Neil Coyle is a member of Parliament from Britain’s Labour Party, considered the moderate left and the current party in power.

“The UK government is committed to certainly trying to reduce the illegal end of migration," Coyle told Full Measure. 

“There are some who feel it's not just unsafe for the people coming over, but some of the people who come are unsafe in this country. But the problem in the UK, as anywhere, is certainly the far right in this country try and lump all migrants together.”

Public pressure to limit immigration has prompted Conservative populist gains across Europe. 

In the UK, two new conservative populist parties have quickly gained traction: Reform UK, now leading both Labour and the Conservatives in popular support. And the even harder-line Restore Britain. Restore officially launched in February, saying Reform wasn’t going far enough.

Amid the political and cultural clashes, the European Parliament is taking action that would have been unheard of a few years ago. Over the summer, it overwhelmingly approved the strictest immigration and deportation law in EU history.

The EU is moving ahead with the steps necessary to implement that new law, with some still promising to try to fight it.

For more on this story, watch "Full Measure with Sharyl Attkisson” Sunday. Attkisson's most recent bestseller is "Follow the $cience: How Big Pharma Misleads, Obscures, and Prevails."