The outpouring of sympathy here for those who died in the terrorist attacks in Paris and of support for France's defense of free speech has been overwhelming, as indeed it has been in so many countries.

Taoiseach (Prime Minister) Enda Kenny, who joined more than 40 world leaders in Paris for the huge solidarity march on Sunday, put it well. "Nous sommes tous Francais aujourd hui – we are all French today," he said.

Here at home there were demonstrations of support in Dublin and elsewhere around the country, and people lined up to sign the book of condolences at the French Embassy. Among the marchers in Dublin and Galway were Muslims who were interviewed on TV and condemned the attacks.

As you would expect, the media in Ireland also registered their sympathy. Journalists in the Irish Independent offices, the biggest newspaper group in the country, stood en masse in silence in the newsroom. It was noticeable, however, that no Irish newspaper was brave enough to show its defiance of the terrorist threat by republishing any of the Charlie Hebdo cartoons.

It was the same in the U.K. That bastion of liberalism and free speech in Britain, The Guardian newspaper, did publish some Hebdo cartoons last week, but not those which depicted the Prophet in an unflattering way. A German newspaper which reprinted some of the most irreverent Mohammad cartoons was hit by an arson attack.

For Irish editors, caution was the better part of valor. It's easy to be cynical about this, of course.

Maybe Irish newspapers should have been brave enough to match their expressions of concern with re-publication of some of the cartoons. But it would be very unwise to dismiss the possibility of a similar attack here in reprisal if that had been done.

We now have a very sizable Muslim population in Ireland, estimated at around 65,000 and predicted to grow to over 100,000 in the next five years or so. Just as it would be completely wrong to say that all Catholics here supported IRA atrocities, it would also be very wrong to suggest that all Muslims are jihadist supporters.

About one third of Muslims here are immigrants and the rest are native Irish converts. The vast majority are peaceful and insist that their religion – the fastest growing religion in Ireland – forbids violence.

But it's not as simple as that. It only takes a small number of radicals to create a problem. That can happen anywhere, including in Ireland, particularly if there are small numbers of immigrants who fail to join in the new society in which they live and become alienated and resentful and begin to search for a cause that will give their isolated lives some meaning.

After the Charlie Hebdo massacre, Dr. Ali Selim, one of the most senior Muslim clerics in Ireland, said that he regarded the attack in Paris as an atrocity and that he believed in free speech. But at the same time he also warned any journalists or papers here who reproduce the Charlie cartoons of Mohammed that he would consider pursuing them through the Irish courts for blasphemy.

At a time when outright condemnation was all that was appropriate, that qualification sent out a somewhat mixed message. It also chimes with the demands made by some Muslims here for complete acceptance of all their beliefs and traditions, including respecting the wishes of those who want to send their daughters to school wearing the hijab or even the niqab. They, like a minority of Muslims in other Western countries, also believe that Irish society must accept that it is wrong to depict the Prophet in a cartoon.

Their expectations of how their beliefs should be accommodated are based on Ireland's embracing of multi-culturalism, the policy that allows or even encourages immigrants to retain their culture and way of life rather than put all their energy into assimilating.

In theory this public policy seems liberal, civilized and generous. But it is a policy that has been a complete failure.

To see that, all we have to do is look at Britain where it is now over 50 years since large scale immigration from India, Pakistan, Bangladesh and the Caribbean began. There are now whole streets in some north of England towns, like Bradford and Leeds, where only immigrants live and where, despite being there so long, some still cannot or choose not to speak English. It was from such a background that the 7/7 London bombers emerged.

This is a legacy of Britain's colonial past; most of its immigrants are from its former colonies. France, thanks to its colonial history in North Africa and particularly in Algeria, has a similar but more difficult problem, with at least five million Muslims, many of them living a marginalized existence on the outskirts of French cities.

Tens of thousands of French-Algerians live in the so-called banlieues (areas of large and run down apartment blocks) outside Paris, where the unemployment rate is four times the national average of 10 percent, where there is little hope. There is, however, crime, drugs and violence, which occasionally explodes into full scale rioting.

There is a striking similarity in the stories of those who carried out the Paris attacks. Losers and no-hopers, from dysfunctional family backgrounds, they drifted into radical action having failed at everything else because it gave them a sense of purpose and self worth. The enormous attention given to them in the wake of the atrocity has tended to give them a status that is completely out of proportion to the pathetic, confused and troubled individuals they actually were.

Much has been made of their training in Yemen, but the aftermath of the shooting, with an ID card left in a car which was crashed a mile away from the scene and the subsequent hold-up of a petrol station when they knew there was a massive search underway, does not say much for their competence. In spite of such ineptitude – maybe partly because of it – they were highly dangerous.

The French handling of the case, in retrospect, also seemed less than impressive. We were told there were 80,000 police and military personnel involved in the hunt. The storming of the Paris kosher supermarket where the second attack had happened also seemed way over the top with a huge force involved.

Most telling is the fact that the attackers were born in France but feel no loyalty to the country that took in their immigrant parents. Instead they have festered in a stew of failure and resentment, feeling marginalized and isolated as they grew up on the fringes of French society.

That is one of the differences between immigrants in European countries like Britain or France and the U.S. In Europe, immigrants hold on to their cultures and beliefs and often harbor great resentment against their new country particularly if they or their kids don't make a success of their new lives.

In the US, in general, immigrants seem to want to become as American as they can, as fast as they can. They may also be Irish American or Polish American, but they are American and proud of it.

There is no doubt that there are lessons in all of this for Ireland. We don't have a colonial past and we don't have banlieues like they have on the northern fringes of Paris.

But we do have high numbers of immigrants – including Muslims – who live in concentrated areas in very deprived suburbs to the west and north of Dublin. There are ongoing tensions in these areas.

Despite all the promises of extra resources that were made during the boom when immigration was encouraged and the desirability of a multi-cultural society in Ireland was extolled, we are left with real problems.

The money to encourage assimilation is no longer available. The extra teachers schools in these areas were supposed to get to help with English language classes did not materialize on anything like a sufficient level. And as the economy crashed, unemployment in these areas soared.

The result is that the social cohesion necessary in these areas is either fragile or missing altogether. The sense of belonging and identity with their new country for some of the immigrants is poor.

That applies to immigrants of all kinds here, and it has to be said that the impression generally is that Muslim immigrants are more successful and self-sufficient than many others. But as we have seen in France, all it takes is a tiny minority of disaffected and angry people to produce a few who may take the path of extreme Islamic fundamentalism and violence.

Although the vast majority of Muslims who live in Ireland are part of mainstream peaceful Islam, it is the disengaged few who may be attracted by jihadi glory that could be a potential problem.

In addition to that, of course, it is also a fact that we have some hard core radicals here who got into Ireland 10 to 15 years ago and managed to get asylum and residency. A few of these hold senior positions in financial support structures for al-Qaeda, and now ISIS, and are well known to both U.S. security and the Gardai (police).

In addition to funding and money-laundering they are also involved in providing false documentation, visas and so on, and more recently some of them are suspected of recruiting young people to fight and have organized training camps in remote locations here.

Some months ago our new Minister for Justice told a committee of the Dail (Irish Parliament) that the Gardai were aware that about 30 suspected jihadis had traveled from Ireland to take part in various conflicts since the start of the Arab Spring. According to the Sunday Independent last weekend, that estimate by the Gardai has since risen to around 50 Irish citizens.

So could a Paris style attack happen here? It is probably unlikely for two reasons.

Firstly, we don't have problems with immigrant communities due to a colonial legacy similar to France or the U.K. Secondly, Ireland is not part of the war against al-Qaeda and Isis.

But we would be foolish to discount the danger completely.

Men entering the Dublin Mosque on South Circular Road.Photocall