The headline began appearing again, as it had so many times in decades past: “What Is A Concentration Camp?”

The debate exploded this week after Rep. Alexandria Ocasio-Cortez (D-N.Y.) insisted that migrant detention facilities along the southern border fit the bill — a position she doubled down on Wednesday night. “We are calling these camps what they are because they fit squarely in an academic consensus and definition,” she wrote on Twitter.

For many critics, using the phrase today dilutes the horrors of Nazi concentration and death camps where millions of Jews were killed. Her supporters, though, argued that Ocasio-Cortez didn’t invoke Nazi Germany or genocide, and that instead she was only using bluntly correct language.

For many historians, both sides of this week’s debate are familiar, mirroring disagreements that have raged for decades over whether Japanese American camps during World War II should be described as concentration camps. In both debates the question has been largely the same: What happens when words become inextricably linked in society’s collective memory with the same atrocity? Is it possible, as one scholar put it, to still use the words “concentration camp” without “trampling the memory” of Holocaust victims?

To Andrea Pitzer, author of “One Long Night: A Global History of Concentration Camps,” it is possible, as long as the context is right. And at the southern border today, she said she believes it is.

“Part of what the toll of the Holocaust did was to reset the bar [for atrocity] so that anything short of that wasn’t even in the same universe,” she told The Washington Post. But, she added, “what I can tell you is, across history, every single camp system has said, ‘We are not like those other camps. Also, these people are dangerous,’ or ‘these people deserve it.' Since the Nazi camps, since World War II, people don’t want to use ‘concentration camps’ because they don’t want to be associated with [Nazis.]”

That much was true in the years after World War II as monuments and museums began to memorialize the more than 110,000 Japanese Americans who were forcibly sent to camps behind barbed-wire fences after the federal government labeled them a national security threat. In 1979, for example, a memorial plaque described the Tule Lake camp as a “concentration camp,” eliciting loud objections from the local community near the Oregon-California border. In a 1979 article titled, “What Makes a Concentration Camp?” the Los Angeles Times reported that the community surrounding the former camp did not want to be associated with the atrocities of the Holocaust. Some acknowledged that the conditions at the camp were bad but argued that it “was no Auschwitz or Dachau.”

But for the detainees, who recalled the watch towers and the guards and the threat of being shot and killed if they tried to escape, “concentration camp” was not by any means a stretch.

“The term concentration camp is not inappropriate,” J.J. Enomoto told the Times. “It was far from a normal living situation. I’m sure our fellow Americans will not be hung up on semantics.”

Nearly 20 years later, Americans were still hung up. A 1998 Ellis Island exhibit drew outcry from the Jewish community and others after the Japanese American National Museum titled it, “America’s Concentration Camps: Remembering the Japanese American Experience.” To the museum’s curators — and to many historians and leading Japanese American organizations today — “internment” or “relocation camps” were euphemisms for the reality of what Japanese Americans endured. President Franklin D. Roosevelt and Supreme Court justices, the museum noted, had both referred to the Japanese American camps as concentration camps.

“We need to call them what they were,” the curator, Karen Ishizuka, told the New York Times in 1998.

Although concentration camps existed long before the Nazis, by 1998 most Americans connected the phrase with Nazi Germany, as Georgetown University linguist Deborah Schiffrin wrote in a 2001 article. The definition of concentration camp had evolved, she wrote, to become “firmly entrenched” in the Jewish identity and story.

David A. Harris, head of the American Jewish Committee, argued to the Times in 1998 that the title of the Japanese-American exhibit “dilutes what we have come to understand as the meaning of concentration camps.'’

''Since the Second World War, these terms have taken on a specificity and a new level of meaning that deserves protection,'' Harris told the newspaper. ''A certain care needs to be exercised.''

Ultimately, Jewish and Japanese American groups held meetings to reach an understanding, Schiffrin reported. The exhibit’s title stayed, but with one long footnote on the flier, making clear that it was not an attempt to directly compare the Japanese-American camps to Nazi camps.

It included a definition that both groups could accept: “A concentration camp is a place where people are imprisoned not because of any crimes they have committed, but simply because of who they are.”

As part of her book, Pitzer adopted her own definition of concentration camps as she traced their history to the turn of the 20th century, during the Cuban War of Independence against Spain and the Second Boer War in South Africa against Great Britain. Pitzer defined them as “mass detention of civilians without trial, usually on the basis of some aspect of their identity.”

She said it’s “factually incorrect and reprehensible” to directly compare the detention of Latin American migrants to a camp like Auschwitz. But she said she felt confident applying the term “concentration camps” to those detained at the border because of the “detention-focused strategy” that greets them upon their arrival, even if they are exercising a legal right to seek asylum. They are typically detained “without regard to individual circumstances,” she said, “treating people as one mass, one group,” and “presenting them as a national security threat to the country and then using as punitive means as the system will allow to detain them.”

Others, however, take a view more akin to the one Harris took in 1998, believing that evoking concentration camps can lead to irresponsible or offensive analogies, even if none was intended — as in the case of Ocasio-Cortez.

Aaron David Miller, a distinguished fellow at the Woodrow Wilson Center, a Washington-based think tank, is among them. It can be dangerous, he told The Washington Post, to cross-compare the conditions and circumstances of the Holocaust, Japanese American incarceration and the detention of migrants at the border. In the case of the latter, he said he fears introducing the “concentration camp” language at all could be distracting, “letting the Trump administration off the hook” because people may immediately think of Nazi Germany and find the comparison absurd.

The issue is one of memory, not definitions, he argued.

“You can’t mess around with people’s memory. Genocide is not unique. But the attempted genocide of European Jewry was in fact unique. And I would disagree with the notion that somehow you can apply a word like ‘concentration camp’ [to migrant detention facilities], however horrific the Trump administration’s approach to migrants and immigration, particularly family separation,” said Miller, who worked as a Middle East analyst and negotiator for the State Department in both Democratic and Republican administrations. “It prevents people from listening, and has a chilling impact on the debate.”

Today, various Japanese American organizations or former camp detainees such as actor and activist George Takei have been vocal in opposition to the migrant detention at the border, particularly of migrant children.

Organizations such as Densho, which educates the public and memorializes the incarceration of Japanese Americans during World War II, and Tsuru For Solidarity have held protests opposing the detention of child migrants at Fort Sill in Oklahoma. The site had been used to incarcerate Japanese Americans during World War II. It had also been used briefly during the Obama administration.

“We will fight back against this country’s plan to bring these concentration camps back at Fort Sill,” Tsuru For Solidarity said in a statement on Twitter.

On Tuesday, after Ocasio-Cortez’s concentration camp comments took off, Takei said: “I know what concentration camps are. I was inside two of them, in America. And yes, we are operating such camps again.”

More from Morning Mix: