The attacks in Paris and the ongoing fear of further attacks in Europe by Islamic extremists have resulted in some shifting in Irish attitudes to the migrant crisis in Europe, and in particular to the number of refugees from Syria we have committed to accepting in the months and years ahead.

This was not evident in the speeches made by politicians in the Dail in the aftermath of the Paris attacks or in most of the commentary in the mainstream media here. But on social media, in calls to radio shows and in letters to the papers, some people here have been expressing concern about what is planned.

We are to take in 4,000 refugees, mainly from Syria, with the first of those due to arrive in the coming weeksrethink their previous open door policies. Across Europe, and particularly in the countries through which the migrants have been passing, there are differing views on how to handle the situation.

Several countries in southern Europe have built fences and closed their borders. Even the wealthier countries in northern Europe have now reached the conclusion -- pushed by growing public concern -- that there is a limit to the numbers they can accept and have introduced much stricter controls.

There is now some doubt about whether the Shengen area -- the 26 countries in Europe which allow free movement between them for their citizens without passport controls -- can continue to operate. Since the Paris attacks, these concerns have intensified.

At least some of those involved in the attacks had moved between