There has been a standing myth that the US has made itself into an impenetrable fortress since the devastating 9/11 attack by al Qaeda a dozen years ago. Washington has never made this claim officially.
And homeland security officials and experts have repeatedly warned that the chance of a terrorist slipping through the cracks of the US’s elaborate security shield was a probability that could never be brought to zero. Nonetheless, the sense that the worst is over as far as terrorism is concerned, definitely international and Islamicist terror, is clearly evident in US policy.
Since the death of Osama bin Laden, President Barack Obama has accelerated the US withdrawal from Afghanistan and has given a sense that he is unconcerned about the consequences of what amounts to an overnight, poorly thought through pullout.
The truth is that the US has never been able to close the portcullis completely, despite the billions of dollars it has spent since 9/11. The US has in recent years experienced two forms of terrorism. One is the front page-grabbing attacks of al Qaeda, other Islamicist groups and homegrown converts inspired by Bin Laden.
The other is an older American brand of terror derived from an anarchist tradition that exists among both the extreme right and left. Both varieties have continued their search for victims despite the post-9/11 measures. Islamicist terrorists successfully evaded the US intelligence system and tried to attempt the ‘underwear’ bombing and the Times Square terror attack.
Both failed to kill anyone only because the terrorists involved did not know how to construct their bombs properly — a matter of luck, not successful policing. There have also been attempts by white supremacists and other domestic groups. But these were relatively amateurish and easily caught.
It remains to be seen who carried out and what motivated the Boston Marathon terror strike. But it should serve as a reminder to the US that it must avoid a narrative that argues it has successfully inoculated itself against terror.
There is no doubt the US has set up a comprehensive and deep counterterrorism strategy. But Washington must recognise that it cannot afford to assume that terrorism is a threat whose time has come and gone. This is an opportunity for the US to adjust its policies at home and abroad to recognise that the war on terror may be over, but the struggle continues.