Two brutal new attacks, a sterile old debate. Islamists slaughter civilians, some of them children, and cue a familiar argument about why. Is it because of who we are, Britain or the West? Or is the root cause rather what we do? It turns out that the two concepts of “being” and “doing” are hard to separate, and this battle of reductionisms won’t help us much. Britain needs to go beyond it. The country and its allies are at war with the Islamic State, objectively if not in full consciousness. Wars normally trigger retaliations. Blowback, like the Manchester attack, is not proof of failure. Reprisal is not defeat. The harder reality is something elected leaders rarely acknowledge: they cannot realistically promise safety. The true bargain on offer, an agonizing one, is that those people are asked to risk increased vulnerability to violence in exchange for a long-term effort to contain and suppress a dangerous movement. The potential for atrocities is not an aberration but built into the war’s logic.

Terrorist motivation, or “why they want to blow us up,” is an old question. The Manchester and London attacks, and their timing, the election season, have blown fresh life into it. Some say it is about “being.” The “being” case goes as follows: the Islamic State, its imitators and affiliates, strike because they hate their victims, the parent society of those victims and that society’s democratic freedoms. In the case of Manchester in particular, they point to a specific pattern, the jihadis’ (and that jihadi’s) loathing of young emancipated women, dancing for pleasure and their preying on children. Terrorism is ultimately caused by terrorists, as agents with little structure in the background. British prime minister Theresa May leads the charge, accusing those who attribute such attacks to other causes of making excuses. A curious authoritarian anti-politics infuses this argument. Violence for a cause is the ultimate political act, so it is hard to keep politics out of it. Yet politicians across the spectrum say that now is not the time for politics, nor should people politicize the issue. Even though democratic liberty is supposedly the engine of the terrorists’ hostility, people must suspend democratic politics, and even though freedom to disagree is at stake, people are urged to remain “united.” Prime Minister May denounces her opponents for exploiting the attack politically, even as she wraps herself in the Union Jack and the mantle of “strength” and hints at new powers for the state.

To underline its causal argument, the “being” camp cherry-picks statements from the killers, and their movement. It isn’t hard to find virulent quotes where Islamists denounce the infidel and their manifold sins, their corruption and blasphemy. Those who attribute Islamist violence to rage against the essence of liberal western societies—against civilization itself—point out the long, eclectic and expanding list of their victims and targets, many having nothing to do with western strategic culpability: Coptic Christians, Japanese aid workers, crucified children, the enslaved Yazidi women, fellow Muslims, the UN headquarters in Baghdad, Palmyran temples and Buddhist statues. It’s not even true that the West routinely fights against Muslims. Western states have undertaken a number of wars in alliance with—or on behalf of—Muslim-majority populations, from aiding the resistance to the Soviet Union in Afghanistan to intervening on their side in Bosnia and Kosovo. Aggrieved jihadis might cite the medieval crusades, but their greatest contemporary opponent, the United States, didn’t even exist to take part. Beneath foreign-policy grievances lies existential rage, or so the argument goes, and the Islamic State is nourished by a pure and indiscriminate hostility. Like the ladies who visited Dr. Johnson and congratulated him for omitting foul language from the dictionary, they crave grievances, and will find them. The root cause, as Mark Steyn once quipped, is that we are all infidels. Notice the structure of this argument: though we must resist violent Islamists who mean us harm, including by force, their violence is built-in, constant, noninteractive and causally unrelated to ours. Western error is largely irrelevant.

Others beg to differ. They say that terrorists attack Western countries because they hate what those states “do” at home and abroad. Western wars motivate and empower the threat. The “doing” camp points to invasions and constant drone strikes, torture and renditions, the botched crusades in Libya, Afghanistan and Iraq. They can also cherry-pick quotes, the virulent statements of revenge and reprisal, the Manchester killer’s apparent indignation at the killing of Muslim children in Syria by Western bombings, or bin Laden’s taunt that if he was fighting America because it was a democracy, then why wasn’t Al Qaeda bombing democratic Sweden? For the “doing” camp, the best way to reduce terror is to reduce the Western provocations that drive and attract it.

Britain’s leader of the opposition, socialist and nuclear-disarmament activist Jeremy Corbyn, makes a point of this, highlighting the links between wars abroad and terrorism at home. What he offers as an alternative is not clear, beyond a vague commitment to political solutions and policing. It isn’t clear what he proposes to do about terrorist networks that lie far beyond the writ of the British state and within firing range. What is clear, however, is his view that retaliation is proof of failure, that the only plausible test of counterterrorism is that it prevents terrorism. This in effect rules out any kind of forceful response, beyond a strictly regulated, civilian law-and-order approach, effectively with the Islamic State left unmolested in the Middle East. Unlike the “being” camp, for whom western error is irrelevant, terrorist violence for the “doing” camp is largely or only caused by western error. While they acknowledge the range of potential predators in this world, this camp has at its core the anti-globalization faction of the Left, with its focus on American Western imperialism and capitalism as the only adversary worth worrying about. If Washington, DC is an illegitimate actor in the world and the world’s main offender, as the likes of the Stop the War Coalition seem to believe, this explains the indulgent attitude they show towards its adversaries.

Neither of these stances will do. Observably, both Western deeds and mode of living antagonize fanatics and attract their aggression. It is absurd to assume that Islamists only attack people who attack them or their coreligionists. The Islamic State is a movement primarily not of protest but of conquest, yearning to restore a lost empire. This gives it an appetite for a whole array of potential targets. It is just as absurd to infer from this observation that western wars and foreign policy cannot be causally implicated. Wars—and in particular occupations—are historic catalysts for terrorism. Iraq, Afghanistan and the cash-and-weapons intervention in Syria were major forces in creating power vacuums, energizing ideological impetus, building violent capability and stoking sectarian division. Libya gave the Islamic State a foothold, and opened up a vortex for Islamist militias to exploit. Even the Australian-led intervention in East Timor, praised by Jeremy Corbyn as one of the few western wars since 1945 he would support, attracted the animus of those emulating bin Laden, given the support it lent to a Roman Catholic majority against a Muslim-majority Indonesia. Errant drone strikes that kill civilians may, in fact, help generate motivation, even as they also damage hard-won capabilities. The trade-offs are difficult. But being at war certainly focuses the adversary’s energy and resources on Britain that might otherwise be directed elsewhere. In that sense alone, Corbyn is right.

Where both camps are wrong, however, is their neglect of the implications of a simple fact: the British state is at war with the Islamic State. Whether or not the term “war” pleases us, pilots are dropping munitions on the Islamic State in Britain’s name, and if you are dropping bombs and if the opponent is firing back, you have a war. Wars involve bloody exchanges and retaliations. Taking a retaliation is not the same, necessarily, as losing. Britain’s armed forces are not merely “on operations.” Its security services are not merely countering “criminals.” Its citizens, whether at rock concerts on in restaurants, are not consumers of security, but are already enlisted. Presenting this as a law-and-order issue to maximize near-term safety makes blowback harder to accept.

The absurd reductio of the “being” camp is that Islamists would attack us anyway. Such an attitude can loosen restraint dangerously. Even if true, Islamists also have their hierarchies of hostility, and the Western-backed assault puts the UK more centrally in the frame. The Islamic State has not so far prioritized its hostilities against South Africa, New Zealand or Venezuela. The absurd reductio of the “doing” camp is that any violent blowback from a policy axiomatically discredits that very policy. That counterterrorist violence can help cause terrorist violence does not necessarily mean it is wiser to renounce all force. Whether or not wars nourish Islamists, we have an interest in denying them control of major cities and resource bases like Mosul, or safe sanctuaries from Somalia to Waziristan. Osama bin Laden himself once recognized the importance of secure operating spaces, urging his affiliates to flee the tribal areas because of disruption and damage of drone strikes.

If you are at war with an aggressive adversary to reverse its long-term power, it is no surprise that it strikes back occasionally. The Nazi Blitz of Britain in 1940–41 was causally linked to Britain's war with Nazi Germany. Going by the logic of minimizing any violence in the near term, would it have been better to renounce war with Nazism in 1940? Some believed so. After all, a misconceived and disastrous war in 1914–18 had helped cause Hitler's rise in the first place, and Hitler offered Britain a negotiated settlement. But the calculus of the British government was more far-sighted. Though belligerence had helped cause Nazism and led to its assaults on the United Kingdom, Britain judged that it couldn't afford to exist only at the permission of a totalitarian state, especially given the record of its barbarous behavior once it conquered other countries. As Churchill judged it, “What I find unendurable is the sense of our country falling into the power, into the orbit and influence of Nazi Germany, and of our existence becoming dependent upon their good will or pleasure.” As ”the lights went out and the bombs went down,” the alternative Churchill offered was not the false assurance of safety, but of stoic persistence and ultimate victory. “London can take it.” Of course, the stakes are lower with the Islamic State. They are more limited, but still real. As we speak, Muslim armies of the Gulf are encircling and grinding down the Islamic State, and evicting them slowly out of Mosul, with the help of western airpower, intelligence, cash and stealth. This is not the end; terrorism will remain chronic for years to come. But it is a major blow, inflicted against an opponent that is suffering defections, losing income and, in the long-term, suffering reversals that will damage its charismatic appeal. Would it be better to leave the caliphate intact, for fear of angering potential radicals at home?

Over a longer arc since 9/11, along with terrible failures and abuses, the cumulative impact of intelligence, police work and military disruption have depleted terrorism within our heartlands—from complex, mass-casualty attacks to frequent failure and often crude attempts. Without again waging unwise wars that blow open vacuums, a slow, patient campaign of disruption, attrition and containment deserves support. But it asks for toleration of costs, sometimes agonizing human costs, in the meantime. Manchester, and London, remind us of the weight of that calculus. Violent outrages of that kind are not unrelated to the conflict we have chosen, but neither are they proof of its folly.

Patrick Porter is the academic director of the Strategy and Security Institute at the University of Exeter.

Image: Remembrance Day ceremonies at Episkopi Garrison, Cyprus. Flickr/Defence Images/SAC Helen Rimmer