Proponents of the hairstyle in question: The rapper Macklemore, left; white-nationalism advocate Richard Spencer, center; and soccer superstar David Beckham, right. (Reuters; Linda Davidson/The Washington Post; Andrew Innerarity/Reuters)

We need to talk about a haircut. Also about identity, and hatred, and maybe about the total end of American civilization — but first about a haircut.

You have seen it. It is short on the sides and long on the top. It is clean and tidy, with a military sheen. It’s been popular among young people for several years. But now this haircut is making us ask ourselves, with seriousness that seems unthinkable in 2016: hipster or Nazi?

Young city-dwelling men leaving their SoulCycle classes in leftover “I’m With Her” T-shirts.

Young white-nationalism enthusiasts leaving a recent conference in Washington, D.C., where several of them performed a Nazi salute.

The same haircut. The exact same haircut.

In the 1930s, Nazis distinguished themselves by wearing swastikas, an easily identifiable marker that made their odious politics clear. The only defining look of today’s white nationalists — a movement that seeks to form a whites-only state — is the haircut, so popular that the leader of one nationalist group tweets under the handle “Fashy Haircut,” short for “fascist.” And there’s nothing inherently wrong with the haircut — as noted, lots of other guys are wearing it these days, too. But that’s what makes it scary.

For the past half-decade, the haircut, when worn by hipsters, has been known jokingly as the “Hitler Youth,” at least according to a 2011 New York Times fashion article, because of its resemblance to the style popular during Germany’s Third Reich. That off-color nickname, one assumes, started in a different political climate, when it seemed we could be a bit cavalier and ironic with such terminology. Back before we started seeing the haircut on literal white nationalists.

Promoters of white nationalism — or the “alt-right,” as some call it — are coming out of the woodwork now. They say they have been emboldened by Donald Trump’s various calls to ban Muslim immigration into this country and deport millions of undocumented Latin Americans. They have a leader in a man named Richard Spencer, who wears the haircut along with his three-piece Brooks Brothers suits. It’s Hitler Youth rebranded as Hitler Yuppie — an insidious way to blend in.

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“I posted on Facebook yesterday that it’s probably time to think about getting rid of my haircut,” says Joseph Phelan, a community organizer and anti-racism activist who lives in Brooklyn and acquired the haircut several years ago at an old-fashioned barber shop. Phelan read a profile on Spencer and was dismayed to learn his haircut is fondly if ironically referred to by many wearers as a “fashy.”

Phelan thinks it’s useful for white nationalists to sport a costume of sorts, so that they might be recognized by the rest of the population. He knows that being upset about a haircut is really being upset about their insidious infiltration into society. “I really wish they would get off my haircut, and get off my people.”

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The style has its origins in Victorian England, when it was worn by young hooligans known as “scuttlers,” but is most commonly affiliated with the Nazi youth movement of the 1930s and ’40s. Adolf Hitler had a version of it — with a floppy, greasy forelock — and so did his close associate Heinrich Himmler, and so did any young man in a Hitler Youth recruitment poster. Apparently, soldiers requested it because it eased the wearing and removing of their helmets. Flash-forward 70-plus years and there were a whole bunch of those haircuts together at the recent conference of Spencer’s National Policy Institute, worn by men who feel their whiteness has been infringed upon by the “cultural Marxism” of the Americas:

There’s an ironic issue with these men wearing this haircut: Since its long-ago heyday, it has been claimed by others, who are not at all connected to fascist worldview. Quite the opposite. Beginning around 2010 or 2011, it became the haircut of Mackle­more, the Seattle rapper. It became the haircut of several cast members of “Glee,” as well as David Beckham.

The haircut that long ago appealed to the Nazis became, more recently, the choice of fashionable young liberal men, gay and straight. Celebrities sent their high-and-tights, as they called them, around the globe, spawning a generation of imitators and obligatory trend pieces, which noted in 2011 that it had become the preferred cut for the well-coiffed, well-clad, crunchy cosmopolitan.

This is not the first instance of a trademark coiffure that spans political divides. Angry racist skinheads and earnest, lefty straight-edge punks have looked similar for decades. Bushy beards can either signify an artisanal pickler or arsenal-holding survivalist. In this instance, what’s ironic is that the men in white nationalism circles are sporting a hairstyle that’s already been repurposed in the 21st century by young people whose ethos is radical safe-space inclusiveness, not ethnophobic separatism with eugenic undertones.

And it’s probably no coincidence. When these groups look and dress like everyone else, it is easier for their extremism to look outwardly normal.

“We call them ‘nipsters’ — neo-Nazi hipsters,” says Long Nguyen, the co-founder of style magazine Flaunt, using a term that became popular in a 2014 Rolling Stone article. “It’s really important for them to make inroads into young people’s culture, in order to expand their base. It’s a lot easier to do that when they’re stealing the look of a familiar hipster style.”

Nguyen says he first noticed this trend in Germany about a decade ago, when young white nationalists were dressing as hipsters, but also as metal heads and hip-hop aficionados. “It’s a little scary.”

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Until a few weeks ago, you saw a man with that haircut and assumed he might be a good person to hit on, or to buy small-batch beer from, or to ask the whereabouts of the nearest bicycle shop. Now you see him and wonder if he’s trying to deport half the nation.

As one hipster wearer of the haircut noted, exasperatedly, on Twitter:

We say this is the wrong attitude. Let’s just make the white nationalists get a different haircut — so the rest of us can identify them. We even have a few recommendations:

The Dorothy Hamill wedge cut. No one’s really worn it since 1980, so it’s all yours.

The double man bun. We really just want to create a taboo around this look.

The Rachel. Remember how every teenage girl in the ’90s wanted to look like Jennifer Aniston on “Friends”? Nazis, you may now have it.

The Trump. The president-elect remains the only practitioner of this hairstyle, which has been described many different ways. Perhaps it’s time your scalp throws its support behind the man you see as your hero.

A mangy mishmash of bald spots and several long strands of hair-stuff that wrap multiple times around your head and smell like cheese and evil: Your hairstyle should reflect who you are.

Thursday, Dec. 1: This story has been updated.