John Allen and Michael O'Hanlon

Let’s give President Trump his due. There is no doubt that our new commander in chief has identified a serious concern, that terrorists could infiltrate the waves of refugees and other individuals surging across the globe. Several recent violent tragedies in Europe, including the catastrophic Bataclan attack in Paris in 2015, involved individuals who had traveled to war zones before sneaking into Europe to carry out their abhorrent plans. Disguising terrorists within otherwise friendly and cooperative populations is a classic tactic for extremist groups.

Indeed, when retired Marine Corps general John Allen was commander in Afghanistan from 2011 through early 2013, for example, Afghans posing as loyal police or army soldiers killed dozens of NATO troops (most of them American) and nearly sank the entire mission. Some who perpetrated these “green-on-blue” attacks might have been mentally unstable. But others gained access to Western personnel in patient and diabolical plots that played out over weeks or months. It is true that this same type of tactic could be attempted among those trying to reach the United States.

At the same time, Trump needs to rapidly reevaluate and revise his executive order on travel and refugees. As it stands, it could do enormous harm to the broader struggle against terrorism — and thus, ultimately, to America's own security even here in the homeland. In particular, it will damage America's image in the world, betray friends and allies who have fought with us, complicate cooperation with governments we need to help us defeat the Islamic State terrorist group, and leave many vulnerable individuals unable to return to jobs and families — or to reach asylum in the first place.

Though the order responds to a legitimate fear, its logic and specific elements are misguided. To begin, none of the major attacks on American soil since Sept. 11, 2001, has involved individuals embedded within refugee or immigration groups from the seven countries involved in the order. Yes, the 9/11 attackers did abuse the immigration system and evade watch lists. But U.S. agencies are now much better at connecting dots and sharing information across the government.

Our vetting has also improved and is very good today. Even if one had doubts, why ban women with their innocent children? There have been only a modest number of female terrorists among today's Salafists and jihadists; hardly any of these are moms. Why ban former interpreters who worked with U.S. forces? They have already proved their trustworthiness, and we owe them a great debt. Why ban anyone older than 50? Terrorists over that age are extremely rare.

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It is difficult to avoid the conclusion that Trump's executive action is poorly thought through and more symbolic than substantive. And while the Trump administration fervently denies that this is a ban on Muslim immigration, many will find it difficult to conclude otherwise given various statements from Trump and his team.

We'd suggest that Trump recast his approach to what is a legitimate issue. For example:

Are there ways to intensify scrutiny on individuals from certain regions of Syria from which ISIL and Al-Nusra have recruited most of their fighters? Young men from these regions might have to undergo an even longer delay — or even a type of probation — to achieve American refugee or immigrant status. Whether this step is truly needed, it would be relatively benign, and understandable.

Can the United States assist European allies to further integrate their watch lists and improve their domestic laws and organizational approaches? There are many U.S. interests and citizens in Europe; we are probably more at risk there than here. We might offer, for example, to deploy some FBI and National Counterterrorism Center personnel to help Belgium, Germany, France and other nations improve their vigilance.

Finally, Trump needs to keep up the fight against ISIL in Iraq, Syria and elsewhere while also brainstorming about ways to end the Syrian civil war. Only more stable, responsive governance in the Middle East can really address the threats we face. There is surely a role for America in improving this capacity. Trump has a chance to bring fresh thinking and better cooperation with Russia. A solution could require consideration of autonomous zones and other forms of self-government for Sunni parts of Syria.

If we're truly seeking to defeat extremism, we should organize to attack the underlying causes of the radicalization that fuels this seemingly interminable Salafist violence worldwide. Above all, we should recognize that it is not about being Muslim or about the Islamic faith.

It is important to take on these challenges early in a Trump presidency, rather than rely on largely irrelevant and in fact mostly counterproductive executive actions of the type taken last week.

John Allen is a retired Marine Corps general who commanded NATO's ISAF mission in Afghanistan from 2011 to 2013 and coordinated the international coalition to counter the Islamic State from 2014 to 2015. Michael O'Hanlon is the author of The $650 Billion Bargain: The Case for Modest Growth in America's Defense Budget. Both are senior fellows at the Brookings Institution.

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