Aaron David Miller is a vice president and distinguished scholar at the Woodrow Wilson International Center for Scholars and author of "The End of Greatness: Why America Can't Have (and Doesn't Want) Another Great President." Miller was a Middle East negotiator in Democratic and Republican administrations. Follow him @aarondmiller2 . The opinions expressed in this commentary are solely those of the author.

(CNN) It's a cruel irony that the worst terror attack in New York City since 9/11 occurred on the watch of a President who boasts that he's done more to combat terror in eight months than Obama did in eight years.

Donald Trump's rhetoric -- that getting tougher on terror will fix the problem at hand -- is not only unrealistic, his focus and methodology are deeply flawed. His travel bans and extreme vetting won't work and may even make things worse. Sure, we need to address flaws in our immigration procedures, but given that radicalization occurs here at home, we need more attention to local outreach in Muslim communities, to identify it and, if possible, prevent it from occurring.

Instead of looking for quick fixes and politicizing the issue, the President should work to reassure the public, even as he prepares the country to accept the reality that it's virtually impossible to prevent the kind of attacks that occurred in downtown Manhattan this week: a suspect drove a rented pickup truck down a bike path, killing eight and injuring about a dozen.

And none of us, especially the President, should lose sight of the fact that extremism is not just a problem involving Muslims; the worst mass shooting in modern American history -- the massacre in Las Vegas October 1 -- was carried out not by a jihadi extremist but by an affluent American citizen living in Nevada.

It's a local problem...

Tragically, Tuesday's attack in New York City drives home a point that terrorism watchers have been making for years. It's impossible to hermetically seal the United States both internally and externally against jihadist attacks. In many respects, we've done an extraordinary job on the external piece. Two oceans and a well-integrated American Muslim community have helped, as have our own improved counterterrorism efforts. Indeed, since 9/11 there has not been a single successful attack planned, coordinated and carried out by ISIS or al-Qaeda operatives.

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Instead, the real challenge we face is from homegrown jihadis. All 13 of the perpetrators of lethal jihadist terrorist attacks in the United States since 9/11 were native-born citizens or legal residents. And both a March 2017 Department of Homeland Security report and a US House Homeland Security Committee report from December 2016 suggest these US-based extremists were likely radicalized only several years after they arrived in the US. It's too early to say, but it should surprise no one if that proves to be the case with Tuesday's vehicular killer.

... and a long-term problem

Americans are impatient and prone to look for comprehensive and quick fixes for complicated problems. We have declared war on drugs; mental illness; cancer; poverty and crime. And yet decades later these battles go on.

Such is the case with the "war on terror." It took the allies six years to defeat Germany and Japan in World War II; and the victory was total. Here we are 16 years after 9/11 and by the looks of things, even with recent successes against the ISIS caliphate in Iraq and Syria, we are nowhere near that kind of victory.

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If defeating the enemy means breaking its will to fight, then we surely are in for a long campaign. Paradoxically, the destruction of the caliphate will only impel the jihadi movement to strike out, to demonstrate its relevance and capacity. Control of territory is an overrated asset in the jihadi world. ISIS and its jihadi derivatives will morph into local insurgencies in Iraq and Syria. Through online contacts and inspiration it will seek to motivate adherents to strike out abroad in Europe and the US, as we've already seen, using less complex tools, such as trucks.

In a free and open society, like ours, in a country where mobility and anonymity are cherished, it's virtually impossible to expect that these attacks with common and everyday weapons can be prevented.

Extreme vetting and travel bans won't fix the problem

We can always enhance our security and look for innovative and effective means to keep us safer, but it is essential that we direct those efforts at solving the problems we actually face. The Trump administration has become too adept at developing solutions for non-problems.

For example, none of the original 9/11 terrorists came from countries that are covered by any of the administration's travel bans; and of the 13 extremists responsible for the fatal attacks since 9/11, none emigrated from or were born into families that emigrated from a country on the administration's original travel ban.

After Tuesday's attack, the President's initial response was to call for tougher border security; restrictions on immigration and extreme vetting, as well as to attack New York Sen. Chuck Schumer for supporting a visa program that, Trump claimed, allowed the truck-driving terrorist to enter the United States.

Not only was the killer's country of origin, Uzbekistan, not on any of the administration's travel bans, the consensus among terrorism experts is that radicalization, in most cases, occurs within the United States . No immigration restriction, even the Diversity Immigrant Visa Program under which the killer was admitted in 2010, would have been able to detect the propensity for radicalization.

That visa diversity program may well be flawed, but we cannot read minds or intuit motivation, particularly if the process of radicalization develops over time. A country-by-country-based set of restrictions simply won't address the problem we face. Indeed, an approach that effectively bans Muslims from entering the US -- as the President wanted to do earlier in his term (and may well be what he would like to achieve) would undermine our nation's values, and in the process alienate the 3 million-plus Muslims in the United States (whose cooperation we need) by stigmatizing them.

We can't secure every jogging or bike path in every large city in America. Educating those who rent trucks about the signs of what might constitute suspicious behavior is a hit-or-miss proposition in a country this large and independent.

More focus on local communities; better partnerships with law enforcement and community institutions, and liaisons and other contact with peers and family members who would be the first to identify signs of radicalization is critically important. Indeed, we need to find more effective ways of identifying radicalization and pre-empting it before it leads to an attack.

But we should have no illusion that this will be easy or successful.

Trump needs to set the right tone

The President's comments Tuesday do precisely the opposite. Focusing on getting "less politically correct" -- Trump's unsubtle reference, during a Cabinet meeting, to toughening up the country's policies toward Muslims -- is the wrong way to go. Attacks by right-wing extremists and jihadis are now nearly equal. And the President's preferences for quick and strict justice for those who allegedly commit these acts of terror raise serious questions about his regard for the rule of law and due process.

The conviction rates for terrorists prosecuted in federal criminal courts i s quite high; federal prosecutors have convicted 200 jihadist related cases, while military commissions at Guantanamo have not convicted a single 9/11 defendant. If the bicycle-path killer were sent to Guantanamo Bay, as Trump suggested Tuesday, it would guarantee a lengthy period most likely without trial and conviction.

There is no question: We must always review immigration procedures, particularly if they've proven to be ineffective and threaten homeland security. But in 10 months of his administration, Mr. Trump has provided very little evidence to suggest he's been much "tougher and smarter" when it comes to preventing attacks at home.

Cutting the budget for programs that prevent terrorism, as Trump has proposed in his 2018 budget, sounds neither tough nor smart. Instead of sounding like a confident President, one who reassures citizens that together we'll surmount the challenge that terror acts present, while maintaining a free and open society consistent with our values, Mr. Trump has sounded like he is on the campaign trail playing to his base.

And immediately after the worst terror attack in New York City since 9/11, that's definitely not what the country needs to hear.