Is ISIS an 'existential threat' to the United States?

ISIS is the apparent perpetrator of the bloody terrorist attacks in Paris on Nov. 13, 2015. But does the group -- also known as ISIL or the Islamic State -- pose an "existential threat" to the United States?

That’s a claim made by at least two Republican presidential candidates.

After the attacks in Paris, Ben Carson told reporters covering the Sunshine Summit for Republican presidential candidates in Florida that "we have to recognize that the global jihadist movement is an existential threat." Sen. Lindsey Graham, R-S.C., said on Fox News Sunday last year that ISIS is "an existential threat" to the United States.

Whether ISIS poses an existential threat to the United States is a question that’s too speculative for us to rate on the Truth-O-Meter, but we also think it’s an interesting and important issue to dissect. So we checked with a number of foreign-policy experts to see what they thought.

Generally speaking, the experts described ISIS as a serious threat to international security -- but they agreed that the group, even in the wake of the Paris attacks, does not qualify as an existential threat to the United States.

The reason has to do with the definition of an existential threat, particularly to a nation as large and powerful as the United States. (Representatives of Carson and Graham did not respond to inquiries.)

What is an ‘existential threat’?

There is no official definition of the phrase, but taken literally, an "existential threat" refers to the continued existence of a nation, its government or its people.

"An existential threat is one that would deprive the United States of its sovereignty under the Constitution, would threaten the territorial integrity of the United States or the safety within U.S. borders of large numbers of Americans, or would pose a manifest challenge to U.S. core interests abroad in a way that would compel an undesired and unwelcome change in our freely chosen ways of life at home," said Ted Bromund, a foreign policy analyst at the conservative Heritage Foundation.

Other experts offered similar definitions.

What have been previous existential threats to the United States?

Whether an entity qualifies as an existential threat depends heavily on the geopolitical framework that defines the target. For instance, it’s not hard to envision an existential threat to Israel, because it’s a small country living cheek-by-jowl with committed enemies. In Israel’s case, a modest number of nuclear bombs could obliterate the country.

For the United States, the threshold for an existential threat is much higher, because of its large population and its geographic location situated between two large oceans, with friendly neighbors to the north and south.

The one clear existential threat the United States has faced during recent decades was the Soviet Union. During the Cold War, the Soviets possessed many nuclear weapons and trained them on the United States -- enough to destroy major U.S. population centers and infrastructure hubs.

Many would add to the list of existential threats Nazi Germany, which during World War II "threatened to seize control of Europe, Africa, and, with Japan, of Asia, which might have enabled it to choke the United States’ trade and eventually mount an invasion," said Barnett R. Rubin, director and senior fellow at New York University’s Center on International Cooperation. "It had developed long-range missiles and was working on nuclear weapons."

The only other widely agreed-upon existential threats to the United States are far older -- and less relevant. These include the British between American independence and the War of 1812, and the Confederate States of America during the Civil War.

Does ISIS qualify as an existential threat to the United States?

We found general agreement that ISIS aspires to become an existential threat to the United States. But that’s not the same thing as actually being one.

Even an attack as devastating and deadly as 9/11 -- which ISIS hasn’t come close to duplicating on American soil -- didn’t topple the U.S. government or threaten its historical status as a constitutional democracy.

ISIS, like other terrorist groups, has "a limited ability to kill civilians in dramatic and destabilizing ways, which in turn forces us to spend inordinate amounts of money and effort on security," said Lance Janda, a military historian at Cameron University. "But they cannot destroy us, or invade, or wreck our economy, or threaten our fleets or armies or air forces in the same way that conventional enemy forces might."

Rubin agreed. "ISIS may or may not be focused on mounting terrorist attacks against the U.S. as it has done in France, but these attacks, while serious, would not be existential threats," he said.

While ISIS may not be an existential threat, it remains a serious threat

Just because ISIS isn’t an existential threat now doesn’t mean the United States can take it easy, however.

ISIS has made clear its contempt for the United States, and it has a stated desire of establishing a caliphate -- an Islamic state led by an absolute religious ruler. Establishing such a caliphate would presumably involve direct governance of a substantial and coherent territorial entity on the ground. With a large enough home base, ISIS might be able to harness "the resources with which to undertake even larger and more disruptive attacks," said Michael O’Hanlon, a senior fellow with the Brookings Institution.

In addition, ISIS is better positioned to bring terrorism to America’s shores than earlier terrorist groups due to its refinement of social media tactics, which have allowed it to recruit from far-flung populations in the West and inspire lone wolves to act on the group’s behalf.

"Many ISIS fighters have come from foreign nations," Bromund said. "If they stayed entirely in Iraq and Syria and were guaranteed to remain merely local, ISIS would simply be a local or regional problem, though still a serious one. But many of these fighters are likely to return to their home nations at some point, and some will return with the intention of carrying out terrorist attacks. While the danger of weapons of mass destruction is still on the horizon, initial reports on the Paris attacks suggest that the danger of returning fighters is now clear and present."

The significance of the Paris attacks, then, would be their expansion of the zone in which ISIS is able to carry out large-scale attacks.

"What has been happening over the past several months – and now potentially with what is going on in Paris – is that the organization is trying to mobilize more significantly against Western targets," said Anthony Clark Arend, a Georgetown University professor of government and foreign service. "So while I am not prepared to say that ISIS currently poses an existential threat to the United States, I see many indications that it may be moving in that direction."

Bromund said he agrees that ISIS is not an existential threat today, but it has at least the possibility of becoming one eventually.

"I am not attracted to the argument that we need to wait for threats to become existential in order to regard them as serious and worthy of concern," he said. "Surely it would be better to consider them seriously before that point."