In the wake of the bombings in Brussels on Tuesday morning, Ted Cruz outlined steps he would take as president to prevent similar attacks in the United States. Within hours, he was forced to clarify his position -- and then defend that clarification from skepticism offered from an unlikely quarter.

"We need to empower law enforcement to patrol and secure Muslim neighborhoods before they become radicalized," Cruz originally wrote on Facebook, a proposal that itself raises a number of questions. What does it mean to "secure" a neighborhood? And where, exactly, are these "Muslim neighborhoods"? The Post's Jim Tankersley tried to answer the second question by looking at where Muslims live in the United States. A version of that map, including the approximate locations of congregations is below.

It's either a lot of neighborhoods or a few, depending on how you look at it. There are a lot of places where a number of Muslims live, but not many where there's a dense Muslim population. San Bernardino County has a relatively light Muslim population, for example, with an estimated 7.33 Muslims for every 1,000 residents. It was also home to Syed Farook and Tashfeen Malik, the married couple that shot and killed 14 of his coworkers last December. How is that lightly-populated "neighborhood" "secured"?

As the day progressed, Cruz's campaign clarified what he meant: Local and state law enforcement should have divisions targeting terror as they would the Mafia or drugs. He additionally pointed to the New York Police Department's efforts after the attacks of Sept. 11th, when the NYPD, under the leadership of then-mayor Michael Bloomberg, surveilled Muslim congregations in the city and beyond. "Mayor de Blasio," Bloomberg's replacement, "succumbed to unfounded criticisms and eliminated the efforts of law enforcement to work with Muslim communities to stop radical Islamic terrorism," the clarification read. Cruz repeated the proposal during a series of TV appearances Wednesday morning.

It didn't take long for the NYPD to disagree.

The department's spokesman, Peter Donald, took issue with the broad sweep of Cruz's comments.

At a press conference on Tuesday, de Blasio and the current police commissioner, William Bratton, echoed that critique.

"I would remind the senator he lives in the United States of America," Bratton said during that press conference, "and the statements he made today is why he's not going to become president of this country -- because we don't need a president that doesn't respect the values that form the foundation of this country."

That's a broad critique of Cruz's general suspicion of Muslims living in America. But in the past, Bratton has also explained that the program Cruz cites -- a program that included infiltrating mosques and sending undercover police to small businesses run by Muslims -- simply didn't work.

Last November, Bratton explained more fully why de Blasio ended the program: "Not one single piece of actionable intelligence ever came out of that unit in its years of existence." That echoes the statements under oath from former NYPD assistant chief Thomas Galeti, who was deposed in 2012 as part of a lawsuit against the force. "Related to Demographics," he said, referring to the internal name for the program, "I can tell you that information that have come in has not commenced an investigation."

The Post's fact-checkers looked at Cruz's claims, by the way. He earned four Pinocchios.

When Cruz appeared at a Republican Party event in Manhattan on Wednesday, he was introduced by a woman who praised his position on Muslim surveillance, noting that former police commissioner Ray Kelly -- the commissioner who implemented the surveillance program -- credited it with breaking up at least 14 terror plots. In 2012, ProPublica assessed that claim. "A review of the list shows a much more complicated reality — that the 14 figure overstates both the number of serious, developed terrorist plots against New York and exaggerates the NYPD's role in stopping attacks," ProPublica's Justin Elliott wrote. Those 14 plots for which Ray Kelly takes credit includes only three in which a government informant wasn't involved or which was a serious plot that was actually pursued. In two of those three cases, the NYPD's role was minor or non-existent. In one, the plot to explode a car in Times Square, the plot failed solely because the explosive mechanism used by the terrorist didn't work.

The American Civil Liberties Union fought the NYPD's program vehemently once it became public. "The NYPD’s surveillance program," it writes, "is based on a false and unconstitutional premise: that Muslim religious belief and practices are a basis for law enforcement scrutiny." This is the thrust of Bratton's objection on Tuesday. Assuming that Muslims need surveillance is an affront.

When he spoke about ending the program last November, Bratton wasn't shy about the argument that the program was successful. "I’m tired. This keeps coming up over and over again in the tabloids," he said. "Let's get real about the issue. It’s urban legend. It’s urban myth."

Its effectiveness, in other words, may be limited to its utility on the campaign trail.