Archbishop of Canterbury Justin Welby has declared the bombing campaign against Islamic State (Isis) a just war.
He said military action was justified on the humanitarian ground that victims of Isis need help in escaping the barbarity of the Islamic extremists.
However, he warned that taking arms is only a short-term solution and that a much wider approach must be taken if the movement is to be defeated.
"There is justification for the use of armed force on humanitarian grounds to enable oppressed victims to find safe space,” he told the House of Lords.
"The action proposed today is right, but we must not rely on a short-term solution on a narrow front to a global, ideological, religious, holistic, and trans-generational challenge."
The archbishop cautioned that the world is facing a struggle that can only be won if the West and its allies can offer a more compelling vision of hope than Isis.
He said: "Isil and its dreadful barbarity are only one example of a global phenomenon. We will not thus be able to deal with a global, holistic danger if the only weapons we are capable of using are military and administrative, and if we focus only on one place.
"We do need to take this action now. But it is also necessary over time that any response to Isil, and to this global danger, be undertaken on an ideological and religious basis that sets out a more compelling vision, a greater challenge, and a more remarkable hope than that offered by Isil."
The archbishop, the Church Times reported, also cautioned that for some Muslim youths in Britain the pull of jihadism is stronger and more attractive than the consumer society they live in.
He said the Anglican and other faith leaders have a role in making sure that disenchantment with certain aspects of Western life does not transform young people into extremists. "Religious leaders must up their game, and the Church is playing its part," he said.
Cardinal Pietro Parolin, the Vatican's secretary of state, told the UN Security Council that terrorism is a “fundamental threat to our common humanity" but added: "International cooperation must also address the root causes upon which international terrorism feeds.”
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