The candlelight vigils didn’t work. After the Manchester Arena suicide bombing in England last month, liberal pundits suggested “mass vigils” and “community solidarity” as a counterterrorism response. The most important imperative, according to the media intelligentsia, was to signal that the West’s commitment to “diversity” and “inclusion” was intact.

Unfortunately, the three Islamic terrorists who used a van and knives to kill another seven civilians and critically injure dozens more in London on Saturday night were unmoved by the “diversity” message. Witnesses described the killers frantically stabbing anyone they could reach, while shouting “This is for Allah”; one witness said that a girl was stabbed up to 15 times.

The “candlelight vigil” counsel has been more muted after this latest attack, though the New York Times has predictably advised the candidates in Britain’s upcoming elections not to succumb to “draconian measures” or to do “just what the terrorists want” by undermining democratic values.

The usual “blame the West” strategy did make an appearance, with some politicians and commentators trying to change the subject from Islamic terrorism to alleged right-wing violence in the U.S. Congressman Adam Smith, from Washington state, reached back to the Oklahoma City bombing to claim that there was a “common thread” of “racism and fear of people who don’t look like you” in the “violence on the other side.” That right-wing violence would only be exacerbated if President Donald Trump’s ideas for fighting terrorism were realized, Smith suggested Sunday on Fox News. Likewise, a spokeswoman from the progressive think tank Demos said that the Trump administration “was tolerating right-wing hate and violence.”

The main response to the London attack, however, has been to reiterate opposition to Trump’s March 2017 executive order briefly suspending new visa issuance from six terror-ridden and terror-sponsoring countries: Iran, Somalia, Sudan, Yemen, Syria, and Libya. That modest three-month pause in new visas for travel to the U.S. was to be accompanied by a thorough review of security screening protocols in those six countries.

On Saturday night, following the London attacks, Trump had tweeted: “We need to be smart, vigilant and tough. We need the courts to give us back our rights. We need the Travel Ban as an extra level of safety!” Trump’s exhortation produced expletive-laden fury, as well as more sober dismay. Columnist Fareed Zakaria summarized two of the main arguments against the visa pause on CNN Monday morning. The pause is a “nonsense solution” to Islamic terrorism, Zakaria said, because the “vast majority” of attacks have been committed by “homegrown terrorists and locals.” In other words, “homegrown” Islamic terrorism is not an immigration problem. But a second-generation Muslim terrorist is more of an immigration problem than a first-generation Muslim terrorist. Such a killer demonstrates that the uncontrolled flow of immigrants from terror-breeding countries has overwhelmed the necessary process of assimilation. When security forces in a country like Britain can no longer keep track of Islamic extremists within their borders, that is a consequence of specific immigration policies.

Zakaria claimed that the problem is “ideology,” not immigration. But how will the West’s ability to counter that ideology be improved by bringing in more bearers of it without a better understanding of who is ripe for radicalization? Until we are confident of our ability to screen for radical Islamic ideology in newcomers and their progeny, the rational reaction is to temporarily slow things down.

Zakaria also invoked a study from the libertarian Cato Institute that allegedly shows that there has not been a terror attack on U.S. soil by a visa holder from the six visa-paused countries since 1975. Therefore, the argument goes, the U.S. could not possibly be attacked by someone from those six countries. But just because something has not happened yet does not mean that it cannot happen. The Trump administration chose the six countries on the travel pause list because, as the Obama administration previously declared, they are the most dangerous breeders of radical Islamic ideology on earth. Several of the countries have no functional government at all. There is no reason to think that the U.S. is immune from the North African-generated terror attacks plaguing Europe, especially if the U.S. mimics European immigration levels.

Trump’s proposed visa pause follows the precautionary principle. Supporters of the Paris climate accords use that principle all the time. They accuse critics of the Paris accords of forcing the world to wait until it is destroyed by a tidal wave before it can take action against climate change. Yet many of those same advocates of the environmental precautionary principle would have the Trump administration wait until the country is attacked by a Libyan, say, before it can tighten visa protocols in Libya. But of course, if the Trump administration did wait until after an attack, it would be accused of overreacting to a one-shot incident. And if the travel pause were broader, to take in countries already associated with terror attacks on U.S. soil, it would be lambasted for its even greater racist, xenophobic reach.

Other pundits and Democratic politicians have resurrected the constitutional arguments against the travel pause. They echo the Fourth Circuit opinion striking down the pause that was issued three days after a second-generation Libyan in Manchester killed 22 people with his suicide vest in May. The Fourth Circuit majority held that the Trump executive order violates the First Amendment’s ban on “laws respecting an establishment of religion.” The majority’s argument is preposterous. The executive order establishes or disestablishes no religion. It has no effect on the vast majority of Muslims worldwide living outside the six covered countries, and it applies to non-Muslims from the six covered countries. Why is Bali not on the list? Because it is not a significant source of terror-breeding ideology and terrorist training. But even if the order had been drawn on religious grounds, foreigners living outside the U.S. have no constitutional rights. The U.S. government owes foreigners on foreign soil nothing when it comes to immigration policy; the equal protection clause and the First Amendment do not apply to them. No one has a right to enter the U.S., or any other country, on his own terms. If the government wanted to suspend visas for blondes, those non-American blondes living abroad would have no standing to challenge the government’s actions.

Courts that have invalidated Trump’s national security orders have tried to finesse those territorial limits by holding that the orders violate the First Amendment rights of U.S. residents. That is a pretextual move. The core impulse behind the judicial rulings to date is to spread constitutional rights worldwide and to dissolve the prerogatives of national sovereignty.

The one potentially valid argument against the executive order now is that the three-month period from the time the order was signed has almost passed. The review of security-screening capacity in the six affected countries could have been completed by now, with or without the travel pause. It could be that such a review can only be thoroughly conducted with visa issuance on hold. Trump officials have not addressed this argument, so it is impossible to say. The main truth of the executive order, however remains in force: the U.S. must review and refine its immigration policies to avoid becoming the next Europe, unable to detect or deter the Islamic terrorists in its midst.

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