Some of the same psychological and political tendencies in the American approach to countering terrorism have been apparent in the use of unmanned aerial vehicles, or drones, to kill suspected terrorists. Lethal operations with drones began in 2002 under George W. Bush, and the Obama administration has increased their pace. The appeal of drones is partly as another splendid hammer that cries out for nails to be struck. More significantly and defensibly, drone strikes have been the only practical way to reach some suspected terrorists in remote places. Adding to their appeal is the same attraction that gives any other use of armed force an advantage over less kinetic tools of statecraft: it brings direct, immediate, tangible results, in this case in the form of dead terrorists. More indirect and intangible are the negative effects, including resentment and radicalization stimulated by collateral damage from the operations. The asymmetry that favors more attention to the first effect than the second—even though the longer-term radicalizing impact may ultimately shape terrorist threats against the United States more than any number of bad guys the drones kill—probably already has pushed the drone strikes past a point of diminishing returns. The results have not been encouraging in, for example, Yemen, where the number of violent radicals has increased during the same period that drone strikes have, even before the effects of the current civil war there began to be felt.

THE MOST intense debates about the use of U.S. armed force are now centered on ISIS and its enclaves in Iraq and Syria, where the ISIS problem is superimposed on a complicated civil war in which a mélange of other opposition groups are also fighting against the Assad regime. Given that ISIS has supplanted Al Qaeda in American perceptions as the embodiment of international terrorism, discussion of what to do about ISIS is heavily weighed down by the baggage of 9/11 and the “war on terror.” Among the consequences are the presumption that military force is the primary tool to wage this “war” and an assumption that if ISIS is not dispatched in the Middle East then it is very likely to harm Americans. A tone of urgency has infused calls to destroy ISIS before it conducts a major terrorist attack in the United States.

More sober consideration would begin by recalling what should be one of leading lessons from the Iraq War: that ISIS did not exist before that war, and that the group (originally Al Qaeda in Iraq) came into existence as a direct result of the civil war that the U.S. invasion and overthrow of Saddam Hussein ignited. Careful consideration of the problem would note that ISIS, unlike the main Al Qaeda organization from which it openly split, rejected the “far enemy” strategy of Osama bin Laden and Ayman al-Zawahiri. ISIS has focused instead on building and defending its so-called caliphate (from the “near enemy”), with any terrorism against the West fulfilling the secondary goals of revenge, recruitment, diversion and deterrence.

Amid the sense of urgency about destroying ISIS’s enclave, little is said publicly about exactly what difference a group’s control of that kind of distant real estate makes for counterterrorism in the United States and the West. Even if some such real estate makes a difference, there is nothing sacred about the ground that ISIS has been occupying in Iraq and Syria. The broader history of Al Qaeda suggests that if there is going to be any base of operations for anti-Western terrorism, it is as likely to be somewhere on the periphery (such as Yemen), as in the group’s original sanctuary. More fundamental is the question of how a terrorist group’s control of any piece of territory affects the West. Experience indicates that such territorial control is neither necessary nor sufficient for significant international terrorist operations. Most of the preparation for 9/11 took place in apartments and flight schools in the West, and in cyberspace, rather than in the Afghan haven. Looking at counterterrorism through a war-tinted lens leads naturally to the equating of progress against ISIS with the movement of front lines on a map, as in conventional war.

What happens in ISIS’s caliphate does affect the group’s ability to inspire violent acts in the West. But these inspirational links may well be a matter of already radicalized individuals looking for a prominent brand in whose name they might commit violent acts they would have committed anyway. The mass shooting in San Bernardino, California in December 2015, which played a major role in stimulating the sense of urgency and alarm about possible ISIS-related attacks in the United States, is instructive. Although the shooters invoked the ISIS name, no evidence has emerged of any organizational connection with ISIS itself. Reportedly, the male half of the shooting pair had sought contact with different extremist groups, including Jabhat al-Nusra and al-Shabaab.

Of the two countries where ISIS has established its enclave, Iraq carries for Americans the baggage of the Iraq War and associated attitudes about sunk costs, but Syria is nonetheless the more complicated situation because of the uprising against the Assad regime. The revolt has regime-change juices flowing, stimulating an American itch to weigh in militarily, rather like what happened with Libya. This itch has spread to the Syrian regime itself, even though the Assads have ruled in Damascus for nearly half a century, so there would not seem to be a reason for urgency in toppling their regime. The impulse to use military force against the regime nonetheless has been strong, as suggested by how much American domestic opponents criticized the Obama administration for making use of a peaceful channel brokered by Russia to dispose of the Syrian regime’s chemical weapons rather than going to war over the issue.

Much of the urging to do more militarily in Syria constitutes inchoate expressions of toughness by politicians or of displeasure with the Syrian mess by others who assume this is yet another problem the United States ought to be able to solve if it applies its power. The relative priorities of confronting the Syrian regime and of dealing with ISIS are often left unclear, as are details of exactly what sort of additional military action the United States might take. The closest things to specificity have been mentions of a no-fly zone and calls for initiation of a ground war against ISIS. For the latter purpose, for example, McCain and former Republican presidential candidate Lindsey Graham have talked about deploying ten thousand U.S. combat troops each to Syria and Iraq.

The idea of a no-fly zone—embraced by, among others, Hillary Clinton—has the attraction of being responsive to the urge to apply more U.S. military force in Syria while sounding less costly than another quagmire on the ground. But although such a zone can be useful where (as with Iraqi Kurdistan in the past) a friendly and well-established authority on the ground could use protection from a hostile force with air power, that is not the situation in Syria. Left unanswered in most calls for a no-fly zone are questions about who controls the ground underneath the prohibited airspace and who will do the fighting to ensure the control stays the way America wants it. Moreover, even just the air component entails a much bigger military commitment—i.e., initiating direct hostilities with the Syrian regime—than those suggesting the idea seem to realize. (Given that ISIS has no air force, a no-fly zone would be useless against that group.) Enforcement of the zone would probably include attacks against Syrian air-defense capabilities and would entail significant risk of direct combat with Russian aircraft flying missions in support of the Syrian regime.

Proposals for U.S. ground operations against ISIS are based on the false premise that “taking out” the group with a quick assault on its positions would be the end of the task. It would not. It would mark the beginning of a new phase of the war characterized by guerrilla attacks, terrorism and other asymmetric operations. Chaos and instability left where the self-styled caliphate once stood would be a fertile garden for additional violent extremism, whether it bore the ISIS name or some other label. There would be no more justification for declaring “mission accomplished” after toppling the ISIS command structure than there was for declaring it in Iraq after toppling Saddam Hussein’s regime. Political scientists Stephen Biddle and Jacob Shapiro assess that taking and holding ISIS’s territory would require not ten or twenty thousand U.S. troops but instead one hundred thousand. In other words, it would be another large, costly and, perhaps, interminable counterinsurgency and nation-building effort.

FOR THE United States to plunge into the Syrian war would play into ISIS’s hands. It would confirm the group’s narratives about it leading Muslim defenses against a predatory West and about apocalypse between itself and the leader of the West. The inevitable collateral damage from increased lethal operations would foster the sort of resentment that aids terrorist recruitment.

Barack Obama, when pressed to do more militarily, has explained the situations in Syria and Iraq in terms that indicate he understands well the aforementioned costs and risks. In his last year in office, he has resisted the pressures to go beyond the approximately four thousand U.S. troops he has reinserted in Iraq, a very small ground presence in Syria and anti-ISIS air operations in both countries. His successor, however, is likely to be someone who will not only have more hawkish views but also, as a first-term president, be more easily moved by the urges and impulses that have pushed the United States into its state of perpetual warfare.