Tony Blair has suggested he may have been naive to think Afghanistan could have been permanently “remade”, even as he issued a strong defence of western interventionism and values days after the UK and US ended their hasty withdrawal from the country.

       The former prime minister, who sent British troops into Afghanistan following the 9/11 attacks 20 years ago, said the chaos that saw tens of thousands flee its returning theocratic rulers showed people identified with western liberal values no matter where they lived.

       Britain and Europe must be willing to defend democracy and free expression in the face of religious tyranny and the threat of terrorism, he said.

       Mr Blair added that he believed making those systems stick in Afghanistan “didn’t fail because the people didn’t want the country remade”, but because the Taliban conquered it through violence.

       “The barrier to nation-building is usually not the people, but poor institutional capacity and governance, including corruption, over many years. And, above all, the challenge of trying to build whilst internal elements combine with external support and try to destroy,” the ex-Labour leader told an audience at the Royal United Services Institute (RUSI).

       Recommended Afghanistan news live: UK into ‘final hours’ of evacuation mission Who are Isis-K? Pen Farthing’s animals could die of heat at Kabul airport

       On Afghanistan, Mr Blair added: “One of the most depressing things I have heard articulated regularly over the past weeks is the idea that we are foolish in believing that western notions of liberal democracy and freedom are exportable, or will ever take root except in the somewhat decadent terrain of western society.

       “Maybe my generation of leaders were naive in thinking countries could be ‘remade’. Or maybe the ‘remaking’ needed to last longer. But we should never forget, as we see the women of Aghanistan in the media, culture and civic society now flee in fear of their lives, that our values are still those which free people choose.

       “Recovering confidence in our values and in their universal application is a necessary part of ensuring we stand up for them and are prepared to defend them.”

       The 68-year-old focused his address on the threat posed by Islamic terrorists.

       Islamism as an ideology incompatible with open societies and a source of violence represents a “first-order security threat” that will strike the west whether it intervenes or not, Mr Blair told the RUSI meeting, rather than a “second-order” one which might be dealt with on a local, case-by-case basis.

       He said the danger to Europe from Islamic jihad was growing and that leading nations should come together to create a coherent strategy for countering it – with a particular emphasis on Europe given the US’ withdrawal from active military engagements.

       That could include working with people in Muslim-majority countries who want to take back control from extremists, as well as helping governments in, for example, the Sahel region of Africa protect their citizens from insurgencies and boost anti-poverty measures, Mr Blair said.

       Such an approach “will likely encompass more than conventional counterterrorism” work, he said, adding: “We needs some boots on the ground. Naturally our preference is for the boots to be local, but that will not always be possible.”