Muslim communities have existed in Europe for centuries.
Guest worker agreements and relaxed immigration policies in the 1960s brought waves of Muslim immigrants from Turkey into Germany, from Algeria into France and from Pakistan into the UK.
However, it is only in the last decade that youngsters born and educated in Europe have tended to become radicalised.
It is now a well- known that both European converts as well as Muslim immigrants have gone to fight in Syria.
France has the largest Muslim population of any European country. It also has the largest number of citizens fighting in Syria with ISIS followed by the citizens of the UK, Germany, Belgium, the Netherlands and Italy.
There are also US and Australian citizens fighting with the Syrian opposition but in much smaller numbers.
There are fears that when these fighters return home more radicalised than ever before they could incite other volunteers towards terrorism.
The recent attack in Paris is seen as a result of both tension between the state imposed secularism in France which is seen as anti- Muslim and the developments in the Middle East.
It is also being said that the Muslim community in the central European countries is being alienated. Marginalization and alienation make such groups radicalised.
Social transformation within the society in Europe is adding to the problem.
It is also an attack on the freedom of expression.
The slow process of radicalisation which is taking place in the European countries has posed a greater challenge to the European governments.
Social media has played a greater role in recruiting Jihadists by making their job easier.
Terror has no religion.
Turkey has become the gateway for Jihadists to Iraq and Syria.