Former British prime minister Tony Blair has welcomed the "important" decision by MPs to authorise British action against Islamic State in Syria.
He claimed European forces had to lead the response to the “threat at our door” and “within our home”.
Mr Blair said defeating Islamic State, also known as Isis, in Iraq, Syria and Libya was part of a wider strategy that also included tackling Islamist ideology.
He warned that a continued failure to recognise the scale of the challenge would lead to terrorist attacks “worse that those in Paris”.
Delivering the Kissinger Lecture at the Library of Congress in Washington, Mr Blair said defeating Islamic State was "only a necessary beginning" because "force alone will not prevail" and "the Islamist ideology has also to be confronted".
He said: “A continued failure to recognise the scale of the challenge and to construct the means necessary to meet it, will result in terrorist attacks potentially worse than those in Paris, producing a backlash which then stigmatises the majority of decent, law abiding Muslims and puts the very alliance so necessary at risk, creating a further cycle of chaos and violence.”
The former Labour leader outlined a five-point plan, including defeating Islamic State and destroying its so-called caliphate; forging a coalition of nations willing to take on jihadist extremists wherever groups attempted to gain a foothold; confronting the ideology; supporting academics and theologians who were tackling extremism; and seeking a wider engagement in Middle East diplomacy.
Mr Blair said: “We should learn the lessons of the whole period from 9/11 to today and try to forge a new synthesis of foreign policy which recognises the need for an active policy of engagement, but in a way sophisticated by our experience not incapacitated by it.
"For Europe, there is a huge calculation to be made. This security threat is at our door. It is actually within our home."