One of the most unchallenged, zany assertions during the war on terror has been that terrorists present an existential threat to the United States, the modern stateand civilization itself. This is important because the overwrought expression, if accepted as valid, could close off evaluation of security efforts. For example, no defense of civil liberties is likely to be terribly effective if people believe the threat from terrorism to be existential.

At long last, President Barack Obama and other top officials are beginning to back away from this absurd position. This much overdue development may not last, however. Extravagant alarmism about the pathological but self-destructiveIslamic State (Isis) in areas of Syria and Iraq may cause us to backslide.

The notion that international terrorism presents an existential threat was spawned by the traumatized in the immediate aftermath of 9/11. Rudy Giuliani, mayor of New York at the time, recalls that all “security experts” expected “dozens and dozens and multiyears of attacks like this” and, in her book The Dark Side, Jane Mayer observed that “the only certainty shared by virtually the entire American intelligence community” was that “a second wave of even more devastating terrorist attacks on America was imminent”. Duly terrified, US intelligence services were soon imaginatively calculating the number of trained al-Qaida operatives in the United States to be between 2,000 and 5,000.

Also compelling was the extrapolation that, because the 9/11 terrorists were successful with box-cutters, they might well be able to turn out nuclear weapons. Soon it was being authoritatively proclaimed that atomic terrorists could “destroy civilization as we know it” and that it was likely that a nuclear terrorist attack on the United States would transpire by 2014.

No atomic terrorists have yet appeared (al-Qaida’s entire budget in 2001 for research on all weapons of mass destruction totaled less than $4,000), and intelligence has been far better at counting al-Qaida operatives in the country than at finding them.

But the notion that terrorism presents an existential threat has played on. By 2008, Homeland Security Secretary Michael Chertoff declared it to be a “significant existential” one — carefully differentiating it, apparently, from all those insignificant existential threats Americans have faced in the past. The bizarre formulation survived into the Obama years. In October 2009, Bruce Riedel, an advisor to the new administration, publicly maintained the al-Qaida threat to the country to be existential.

In 2014, however, things began to change.

In a speech at Harvard in October, Vice President Joseph Biden offered the thought that “we face no existential threat — none — to our way of life or our ultimate security.” After a decent interval of three months, President Barack Obama reiterated this point at a press conference, and then expanded in aninterview a few weeks later, adding that the US should not “provide a victory to these terrorist networks by over-inflating their importance and suggesting in some fashion that they are an existential threat to the United States or the world order.” Later, his national security advisor, Susan Rice, echoed the point in a formal speech.

It is astounding that these utterances — “blindingly obvious” as security specialist Bruce Schneier puts it — appear to mark the first time any officials in the United States have had the notion and the courage to say so in public.

Whether that development, at once remarkable and absurdly belated, will have some consequence, or even continue, remains to be seen. Senators John McCain and Lindsay Graham have insisted for months that Isis presents an existential threat to the United States. An alarmed David Brooks reported that financial analysts have convinced themselves that the group has the potential to generate a worldwide “economic cataclysm.”

And General Michael Flynn, recently retired as head of the Defense Intelligence Agency, has been insisting that the terrorist enemy is “committed to the destruction of freedom and the American way of life” while seeking “world domination, achieved through violence and bloodshed.” It was reported that his remarks provoked nods of approval, cheers and “ultimately a standing ovation” from the audience.

Thus even the most modest imaginable effort to rein in the war on terror hyperbole may fail to gel.