Tony Blair, the former British prime minister, has said that Western politicians should not rule out sending troops on the ground into Iraq - and that they should listen to him because of his experience of going to war in the country.
In a BBC interview, and separate 6,500 word essay on his Faith Foundation website, Blair claims that the wars fought in Afghanistan and Iraq which came to define his premiership have provided invaluable experience in how to tackle the Islamic State.
He told the BBC that people should "appreciate" that he has learned lessons from the Iraq war and that his thoughts on tackling the Islamic State are valuable because they are "precisely" the same terrorist forces he fought.
Still reviled by British opponents of the 2003 Iraq invasion, Blair has since the recent explosion in violence sought to defend his record in the country, using a string of media interviews to insist that the current crisis is not a result of the Western intervention that he and George W. Bush led.
In this latest interview, Blair said that Islamic State militants are "brutal" and "prepared to die without regret," making them a fanatical force that can be contained but not destroyed with airpower alone.
He acknowledged that there may be "no appetite" for a ground fight, but said it may become necessary.
His comments were echoed by a 6500-word essay, published on his Faith Foundation website, which outlined a "strategy to counter religious extremism."
He wrote that the difficulties encountered were "in part intrinsic" to the nature of the battle currently being waged, and the lessons learned from those conflicts had assisted the West's "capacity and capability" to fight Islamic State militants.
David Cameron, the current British prime minister, is expected to discuss plans with Barack Obama regarding British air strikes, but there are no plans to commit British troops.
In the essay, Blair warns that air strikes may not be enough to defeat the jihadists.
He writes: "this is the hard truth - air power alone will not suffice. They can be hemmed in, harried and to a degree contained by air power. But they can't be defeated by it."
He argues that parts of Muslim society have developed a view of the West that is "innately hostile" and that the spread of extremist teaching in the UK is "much more frightening than you would think".
Blair is currently the Middle East peace envoy, tasked with negotiating a ceasefire in times of conflict, a role he has held since 2007.
In July, as the Gaza death toll passed the 1,050 mark, he returned to London to host a 60th birthday party for his wife Cherie — featuring comedian Bobby Davro.
He has also come under fire for only visiting Gaza twice - both times in 2009 — citing security reasons.
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