Twenty years after a series of co-ordinated attacks killed nearly 3,000 people and devastated the totems of American economic and military might, the full legacy of the September 11 attacks has yet to be written.
The enduring horror of that day has defined the new millennium, sparking ruinous wars and vexed attempts to reconcile national security interests with civil liberties.
In Scotland, 14 years have passed since the Glasgow Airport bombing, the first and only Islamist-inspired terror strike on this nation’s soil. But the threat of another attack remains substantial, and the nature of the threat has changed markedly.
The question of whether we are safer is complicated by consequences yet unknown from one of the attack’s bloodiest repercussions: namely, the conflict in Afghanistan.
The abrupt withdrawal from the country by the US, the UK and their NATO allies has reignited fears of a resurgent al-Qaeda, IS, and other hardline jihadist groups.
US president Joe Biden has expressed confidence in the capability of ‘over the horizon’ surveillance to mitigate the loss of on-the-ground intelligence, but experts are less sure.
“It’s second best,” reasoned Dr Tim Wilson, director of the Handa Centre for the Study of Terrorism and Political Violence at the University of St Andrews. “The question now is how warm is our alliance with the Taliban – an alliance or convergence of interests nobody will admit to.
“There are conflicts between the Taliban and local ISIS affiliates, and jihadist circles can be overlapping. There’s also a very complex relationship with al-Qaeda. Is it willing to knuckle under in the way the Taliban seems to be publicly proclaiming?
“The withdrawal will undoubtedly embolden some elements amongst Islamist groups. How that plays out is hard to call.”
One of the most controversial repercussions of 9/11 and the 7/7 London bombings in 2005 was the legislative response, in particular the Anti-Terrorism, Crime and Security Act 2001 and the Terrorism Act 2006.
Helen Fenwick, professor of law at Durham University, who specialises in the intersection between human rights and counter-terrorism laws, pointed out the former act’s power to detain suspected foreign terrorists without trial was later abandoned after it was found to breach the European Convention on Human Rights.
On the whole, however, she believes counter-terrorism measures have gained public acceptance.
“That acceptance has become greater over the last 20 years, especially in the wake of particular atrocities, including the Manchester Arena attack,” she said.
But Amnesty Scotland pointed to the backlash to Police Scotland’s use of stop and search powers, adding: “There’s no question that the response to terror threats is disproportionate in this country, and that the trend is towards increasing state overreach.”
While terror threats abound elsewhere, one of the most pronounced shifts over the past 20 years has been the surge in home-grown plots.
Since 2001, some 4,907 people in the UK have been arrested for terrorism-related activity. Of those, 1,004 were convicted.
The most recent Home Office data shows that in the 12 months to the end of March this year, there were just 14 prosecutions and 13 convictions, the lowest total since 2001.
That is not the only change. In 2013, there were just four individuals in custody across the UK for terrorism-related offences waged in the name of extreme right-wing ideologies.
Eight years on, the figure is 44. Conversely, the number of individuals in custody classed as Islamist extremists has fallen for three years running.
The trend is also reflected in the four terror groups newly proscribed since 2020. All share a far right or white supremacist ideology.
Dr Wilson said he believed the proliferation of far-right groups was, in part, a reaction to 9/11.
“Tensions with Muslim communities in the far right existed before 9/11, but the idea of ‘the enemy within’ has increased mobilisation,” he explained.
“There’s a phenomenon of reciprocal radicalisation where Islamist and far-right extremists monitor each other and copy tactics. But there are other drivers, such as social media, austerity, and an uncertain economic model.”
Given counter-terrorism is a reserved matter, assessing the seriousness of the threat posed by domestic right-wing extremists to Scotland is complicated, but data collated for Prevent, the controversial terrorism-prevention programme, is telling.
In 2017/18, the number of referrals in Scotland over concerns related to international extremism stood at 38. By contrast, there were only 23 referrals concerning extreme right-wing ideologies.
The latest data, which covers the 12 months to March 31, 2020, shows just five people were flagged in connection with international extremism. Some 21 were referred for right-wing extremism.
How authorities in Scotland and the rest of the UK counter these twin menaces will be a grave test.
So are we safer now? The answer is affirmative from Prof Fenwick.
“Yes, in that intelligence techniques, security in certain buildings and transport, data sharing between states, and criminal offences of preparing for terrorist acts, are all more advanced,” she said.
As for Dr Wilson, the answer is also yes, albeit with important caveats attached.
“If the threat is considered in terms of a global network of terror cells, the answer has to be yes, western countries are safer,” he said.
“Security services are better resourced and better understand what motivates Islamist groups. But against that, the growth of social media and communications technology has had a destabilising effect on our politics.
“Out of that potentially comes a different threat, which is much less disciplined, hierarchical, or cellular, and more about large-scale disorder, mayhem, and declining trust in our institutions. We’re still getting our head around how to manage that.”