Military intervention is needed to ensure Islamic State is "crushed", Tony Blair has said.
The former UK prime minister described the attacks in Brussels as "shocking", but said the attacks would keep on coming unless extremism was tackled.
Writing in the Sunday Times, he said that the roots of Islamism, including the immaturity of political systems and the exploitation over a genuine sense of injustice over the Palestinian issue, needed to be understood in order to counter it.
Mr Blair argued that a new strategy was needed to defeat extremism that included greater co-operation between intelligence agencies.
An effective system of processing refugees was also needed to stop the security risk of uncontrolled flows of people across Europe, he said.
But he also argued that IS, also known as Isis, needed to be eliminated more quickly.
Mr Blair said: "We can use local allies in the fight, but they need equipment and where they need active, on-the-ground, military support from us, we should give it.
"The Americans are doing this now - at least to a degree and with effect.
"But to have allowed Isis to become the largest militia in Libya right on Europe's doorstep is extraordinary. It has to be crushed."
Mr Blair founded the Tony Blair Faith Foundation, which provides practical support to counter religious conflict and extremism. He previously served as peace envoy to the Middle East and works in eight African countries advising presidents.
He was prime minister during the 2003 invasion of Iraq and is expected to come in for criticism in the official inquiry report into the Iraq war - the Chilcot report - when it is finally published.
In the article he called for Western ground forces to take action wherever a terrorist group emerges, as they are necessary to win the fight against extremism.
He said that in the long term, education promoting religious tolerance and effective aid and development policy needed to be prioritised.
