The west still faces the threat of 9/11-style attacks by radical Islamist groups but this time using bio-terrorism, Tony Blair has warned.

Blair also challenged the US president, Joe Biden, by urging democratic governments not to lose confidence in using military force to defend and export their values.

In a speech to the defence thinktank Rusi marking the 20th anniversary of the 11 September 2001 al-Qaida terrorist attacks on the US, Blair, who was British prime minister at the time , and supported military interventions in Iraq and Afghanistan, insisted the terrorist threat remained a first order issue.

He suggested “the pressure of short-term political imperatives is giving both allies and opponents of liberal open societies the belief that ‘our time is over’”.

He said he found it deeply depressing to hear western opinion claim “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.”

He insisted that “despite the decline in terrorist attacks, Islamism, both the ideology and the violence, is a first-order security threat; and, unchecked, it will come to us, even if centred far from us, as 9/11 demonstrated. Covid-19 has taught us about deadly pathogens. Bio-terror possibilities may seem like the realm of science fiction; but we would be wise now to prepare for their potential use by non-state actors.”

He suggested radical Islamism could not be confronted solely by drone strikes, surveillance and special forces. He challenged the US president by saying nation-making must be a tool in the armoury, saying a mix of hard and soft power may still be required. By contrast, Biden has said the end of the 20-year US intervention in Afghanistan turns the page on an era of nation-building.

Blair admitted in the US there was “now an overwhelming political constraint on military interventions” but said this represented a challenge for Britain and Nato. He believes the loss of the will to fight, combined with an inability to think strategically represents a real self-imposed threat. He warned: “If the enemy we’re fighting knows that the more casualties they inflict, the more our political will to fight erodes, then the incentive structure is plain.”

He implicitly accepted nation-building as practised in Afghanistan failed, and leaders may have been naive about how it could be achieved, or how long would be needed.

But he stressed “our ‘remaking’ didn’t fail because the people didn’t want the country ‘remade’. For sure, we could have ‘remade’ better, but Afghans did not choose the Taliban takeover. The last opinion poll in 2019 showed them with 4% support among the Afghan people. They conquered the country by violence not persuasion. The barrier to ‘nation-building’ is usually not the people, but poor institutional capacity and governance, including corruption, over many years; and most of all the challenge of trying to build whilst internal elements combined with external support are trying to destroy.”

Blair does not name the external elements, but he has long believed Pakistan supported the Taliban.

He added: “For me, one of the most alarming developments of recent times has been the sense that the west lacks the capacity to formulate strategy. That its short-term political imperatives have squeezed the space for long-term thinking.

“It is this sense more than anything else which gives our allies anxiety and our opponents a belief our time is over.”

Blair said the coming elections in France and Germany represented an opportunity for the UK to rebuild European relationships, possibly building out from the existing bilateral defence relationship with France.

He said he was deeply concerned that north Africa and the Sahel represented a future security threat for the whole of Europe, saying “we do not have the capacity to help those countries govern their space or get on their feet”.

“Are we going to let the situation fester until finally we get waves of extremism and waves of migration coming from there, or are we going to deal with it?”