It’s clear that President Trump really, really wants his “travel ban” to become a defining issue for his administration. His Justice Department just filed an emergency motion with the Supreme Court asking the justices to overturn lower-court decisions preventing his executive order from taking effect. The question is: why?

His desire for this executive order seems even more divorced now from the actual requirements of fighting terrorism than it was when first issued on January 27. Trump inadvertently illustrated this himself on Saturday when, just minutes after a terror attack in London, he 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!” He then implied that it was only political correctness that was stopping the ban from being implemented. “We must stop being politically correct and get down to the business of security for our people,” the president wrote. “If we don’t get smart it will only get worse.”

Mind you, there was no evidence when he wrote those words that the terror attack on London Bridge was carried out by citizens of Libya, Somalia, Sudan, Syria, or Yemen, the six countries affected by the ban. Indeed, there have been no terror attacks carried out anywhere in the West this year by citizens of those states. Salman Abedi, the Manchester bomber, was of Libyan extraction. He was born in Britain and was a British citizen, and, therefore, would have been free to travel to the United States even if the travel ban were in effect.

The original justification for the executive order on January 27 was that the United States was at such heightened risk of attacks from foreign jihadists that it was necessary to place a 90-day suspension on all entry from seven Muslim countries (Iraq was later dropped from the list). The speciousness of this justification is evident from the fact that, 129 days later, there still have not been any Islamist terrorist attacks in the United States. There hasn’t even been any evidence of foiled plots carried out by nationals of the six target countries.

Surely, Trump isn’t claiming that we need a 90-day pause starting now because his administration hasn’t been able to study the problem and issue an effective response during the previous 129 days? That would be quite an admission of failure on the administration’s part. In reality, of course, all of the evidence points to the fact that our border vetting programs were already effective when Trump took office and didn’t need much reform.

Yet the president continues to agitate for his “travel ban”—in the process making a mockery of his aides’ attempts to claim that it’s not a travel ban. (On May 28, Secretary of Homeland Security John Kelly insisted on Fox News that “it’s not a travel ban, remember. It’s the travel pause.”)

On Monday, Trump bizarrely blamed his Justice Department for submitting a “watered down, politically correct version” of the ban to the Supreme Court—when he was the one who signed the watered-down version in order to try to pass judicial scrutiny.

The original order had affected existing visa holders, causing chaos at the airports; the new version did not cancel existing visas. But with these tweets, Trump is undermining his chances of success in the Supreme Court. He is furthering suspicion that his goal all along is to enact some version of his obviously unconstitutional proposal from December 2015 for “a total and complete shutdown of Muslims entering the United States until our country’s representatives can figure out what the hell is going on.” Even Dick Cheney said that a Muslim ban “goes against everything we stand for and believe in.”

What can explain Trump’s fixation with a travel ban? Perhaps he still doesn’t understand the issue. Perhaps the president, unable to move his legislative agenda through Congress, is intent on throwing symbolic red meat to his supporters. Perhaps he doesn’t really care whether his ban is enacted and would prefer, in fact, for it to become a martyr for his populist politics so that he can try to scapegoat the judiciary for the next terrorist attack in the United States.

Who knows what he’s thinking? The only thing that’s clear is that we don’t need a travel ban to keep us safe, and agitating for one is a distraction from the true challenges of counter-terrorism. Rather than grand-standing on this issue, Trump would be better advised to take steps to win the confidence of Muslims so that they will be more likely to inform on potential terrorists in their midst.