Donald Trump Jr. criticized London Mayor Sadiq Khan following the city’s deadly terror attack Wednesday for saying in September that terrorism threats are a part of urban life and officials must prepare accordingly.

You have to be kidding me?!: Terror attacks are part of living in big city, says London Mayor Sadiq Khan https://t.co/uSm2pwRTjO — Donald Trump Jr. (@DonaldJTrumpJr) March 22, 2017

Khan’s remarks were taken out of context this week, but they do reflect a pragmatic view of counterterrorism efforts. Population centers with famous landmarks are an obvious target for people looking to inflict harm and fear ― as was the case with London’s Houses of Parliament, which the attacker tried to storm Wednesday.

Cities “have got to be prepared for these sort of things,” Khan said in September.

“That means being vigilant, having a police force that is in touch with communities, it means the security services being ready, but also it means exchanging ideas and best practice,” he told the Evening Standard at the time.

His response to Wednesday’s attacks reflected that viewpoint, primarily focusing on the work of first responders, rather than the suspects or raising alarm among Londoners.

“We won’t be cowed by terrorists,” Khan said. He also declined to comment on the criticism President Donald Trump’s eldest child had aimed at him, pointing out that he had “more important things” to do.

But the issue at hand isn’t a Twitter spat between Khan and Donald Trump Jr. It’s a fundamental disagreement on how societies should respond to terrorism, and what resources should be used in preventing and responding to those incidents.

On one side is the U.S. president and his followers, who are in favor of bolstering defense budgets with billions of dollars, banning travel from Muslim-majority countries and reorienting policy around eradication of terrorism. On the other, there are those that agree that terrorism is a serious issue, but one that should be addressed in a measured, non-overbearing way.

Those on the latter side have often been ridiculed as “soft” on terrorism. But the approach has some prominent adherents, including former President Barack Obama. The Atlantic’s Jeffrey Goldberg reported last year:

Obama frequently reminds his staff that terrorism takes far fewer lives in America than handguns, car accidents, and falls in bathtubs do. Several years ago, he expressed to me his admiration for Israelis’ “resilience” in the face of constant terrorism, and it is clear that he would like to see resilience replace panic in American society. Nevertheless, his advisers are fighting a constant rearguard action to keep Obama from placing terrorism in what he considers its “proper” perspective, out of concern that he will seem insensitive to the fears of the American people.

The other camp favors rhetoric calling for the eradication of terrorism ― a goal experts say is unlikely to come to fruition. And earlier calls to manage the problem, rather than seek to get rid of it altogether, have been met with fierce criticism from conservatives. (See, for example, the 2004 backlash to then-presidential candidate John Kerry’s call to reduce terrorism to a “nuisance” level.)

But William Braniff, the executive director of the National Consortium for the Study of Terrorism and Responses to Terrorism, said there’s a strong case to be made for responding to terrorist attacks the same way a leader would respond to other violent crime. Doing so can “take the sting” out of an attack, Braniff said, by not playing into the political motivations typically behind such events.

Braniff said Khan is right to prepare for future attacks as an inevitability.

“It’s not a question of if, unfortunately, it’s a question of when,” he said.

Khan’s tactic, Braniff said, is a form of “political resilience,” an idea detailed by START researcher Clark McCauley in a 2012 opinion piece. In other words, in addition to infrastructure preparations and emergency planning, leaders should also prepare constituencies for the inevitability of future attacks, so that they do not constantly live in fear about the possibility of terror, nor have a false sense of security.

“It’s a sober approach to a violent threat, but to pretend like a government can provide 100 percent security without taking on really authoritarian measures is really leading the public along,” Braniff said. “It’s setting them up to be more intimidated, more terrorized or more angry in response to these kinds of incidents.”

Andrew Bacevich, a military analyst and professor of history and international relations at Boston University, offered a similar perspective on the inevitability of attacks in urban centers.

“Criminality is inherent in urban living,” he wrote in an email. “Terrorism is simply a form of criminality, albeit one that afflicts some cities more than others. The key point is that no city is free from violent crime, to include the one in which Donald Trump, Jr. resides.”

“This is another case where the Trumps and their supporters have embraced this crazy myth that you can completely eradicate terrorism,” said Daniel Benjamin, who served as a coordinator for counterterrorism for the State Department and is now the director of the Dickey Center for International Understanding at Dartmouth College. “That’s absurd. For as long as we’ve had dynamite, we’ve had terrorism.”

Benjamin said American politicians would be wise to follow Khan’s example, noting that gun violence kills far more Americans annually than terror attacks do.

“One of the mayor’s chief responsibilities is to get things back to normal as quickly as possible,” he said. “That denies the terrorist even bigger gains from those actions, in terms of paralyzing a population. It lowers the value of a strike against a civilian target.”

Like Obama, he pointed to Israel, where leaders have adapted to the constant threat of terrorism.

“It would be crippling for these populations” to dwell on attacks, he said.

J.M. Berger, a fellow with the International Centre for Counter-Terrorism, agreed that leaders “can’t reasonably hope to completely eliminate” the threat of terrorism.

“I think large and medium-sized cities obviously need to prepare for the possibility of terrorist attacks, and I can’t understand why Donald Trump Jr. or anyone else would find that idea controversial,” he wrote in an email.

Brian Dillon, a British counterterrorism expert, offered a similar assessment of how cities should address terrorism during an interview with MSNBC earlier this week.

Crucial and perhaps even obvious reminder in wake of a terror attack like today's in London. From @rubi_res on MSNBC. pic.twitter.com/p8C82i2t1l — Nick Wing (@nickpwing) March 22, 2017