Donald Trump, still getting used to using a teleprompter, stumbled a bit from his prepared remarks during the speech on terrorism he gave in New Hampshire on Monday. Referring to the man who killed 49 people at a gay nightclub in Orlando, he intended to say that, "The killer, whose name I will not use, or ever say, was born to Afghan parents who immigrated to the United States." Instead, he said that the man was "born in Afghan, of Afghan parents who immigrated to the United States." (Some people heard “born an Afghan” — but either way, clearly a mistake.)

He went on:

His father published support for the Afghan Taliban, a regime which murders those who don't share its radical views, and they murdered plenty. The father even said he was running for president of Afghanistan. The bottom line is that the only reason the killer was in America in the first place, was because we allowed his family to come here.
That is a fact, and it's a fact we need to talk about.

It is a fact. And it's a fact that reveals why Trump's plan to ban Muslims from entering the country* is tricky.

The Orlando shooter, Omar Mateen, was not born in "Afghan." He was not an Afghan or a foreigner of any kind. He was born in New Hyde Park, a neighborhood in the Queens borough of New York City, northeast of JFK airport. His parents, as Trump notes, were immigrants from Afghanistan; his father is still involved in Afghan politics.

What's remarkable about that biography is that it also, to a large degree, describes Trump.

Trump was born a bit to the west in a wealthier Queens neighborhood, but only about five miles from the neighborhood of Mateen's birth. (The map shows his childhood home in Jamaica Estates.) And Trump is also the child of an immigrant: His mother was born in the United Kingdom and grew up in Scotland.

Trump would surely argue that there have been far fewer terrorist attacks committed in the United States in recent years by the children of people born in the United Kingdom than there have been from the children of people born in the Middle East. But, as has been pointed out repeatedly, those attackers are a small minority of all people who share that lineage. There are thousands of Muslim congregations across the United States — 2,106 as of 2010, according to the U.S. Religion Census. The United States is home to an estimated 2.6 million Muslims.

That's people of the Muslim faith who are already here, who have been living here for years, are citizens or were born here — and essentially none of whom plan to conduct a terrorist attack against the United States.

At the heart of Trump's ban, then, is the point that whom we let into the country now probably bears no relationship to who might be in conflict with the United States in the future. Mateen's father probably came to the United States as part of a flood of refugees after the Soviet occupation of Afghanistan. In the 1980s, Afghan freedom fighters were allies of the United States; in 1983, President Ronald Reagan even met with some.

It's not impossible to imagine an alternate history in which we now face a threat from Scottish insurgents, bent on wreaking havoc in the United States or, in Trump's words on Monday, against "Europe or our allies." Irish revolutionaries conducted terrorist attacks against our ally Britian for years. What if Trump's mother had been from Ireland instead of from Britain?

Banning Muslims now might prevent some Islamic State fighter who managed to figure out a path across the Atlantic Ocean but who couldn't figure out how to mask his faith. But it does nothing about people like Mateen, who were born in the United States.

It does nothing about anyone born in Queens to an immigrant from somewhere else on the globe.

*During his speech from New Hampshire, Trump insisted that the ban would be temporary, until the government can "perfectly" screen those seeking entry.