Good reminder:

The Republican National Convention hit rock bottom on its third day in Milwaukee, Wis., on July 17, with a sea of signs calling for “Mass Deportation Now.” If former president Donald Trump is elected for a second term, he and his advisers promise to remove from the U.S., via forced expulsions and deportation camps, as many as 20 million people—a number larger than the country’s current estimated population of undocumented residents. Put into effect, this scheme would devolve quickly into a vast 21st-century version of concentration camps, with predictably brutal results.

Concentration camps are built for the mass detention of civilians based on group identity, excluding protections normally afforded by a country’s legal system. I wrote a history of these camps that traced an arc from their 19th-century origins in Spanish-occupied Cuba through the development of death camps in Germany and their modern-day descendants around the world.

Trump’s plan to launch a massive deportation project nationwide—the first plank in the platform approved at his party’s convention—draws on the same flawed historical rationales and pseudoscience that built support for concentration camps worldwide in the 20th century. Early architects of these camps veiled their efforts in scientific terms while using terror and punishment to seize more power.

For example, Trump has claimed repeatedly that undocumented immigrants are “poisoning the blood” of the U.S. “Blood poisoning” is a medical condition; saying that foreigners are poisoning a nation’s blood is simply a slur. But perverting scientific or medical language to violate human rights and permit atrocities comes from a familiar playbook.

Justifications for brutal immigration policies have often distorted scientific goals of public health programs. Trump and his advisers have long been prone to panic-mongering over the threat of disease from immigrants. They’ve likewise twisted sociology to stoke anxiety about assimilation to justify a Muslim ban or to try to make racist comments seem less objectionable. Even simple principles of statistics get skewered as Trump lies about crime committed by immigrants.

Trump’s incendiary language echoes dangerous historical precedents. He has called his political opponents “vermin,” referred to immigrants as depraved“animals” and “rapists,” and described the U.S.–Mexico border as an “open wound.” Examples abound of similar rhetoric in Nazi propaganda about Jews.

Less well known is the fact that before World War II, the Nazis framed German Jews as aliens who needed to be forced into emigration or expelled. This was the original logic for stripping Jews of citizenship: to officially render them foreigners. (It should be noted that Trump aims to end birthright citizenship in the U.S.)

Prejudice has always been a part of concentration camps. At the dawn of the 20th century, mortality surged in British camps in southern Africa during the South African War, with children’s deaths blamed on “uncivilized” Boer mothers. Embracing pseudoscientific biology, camp administrators spent about half the money per day for food for a Black African civilian as was spent on white detainees (who themselves received insufficient rations). Bureaucracy and unforeseen crises added immeasurably to the harm. In poorly sited and badly run camps, tens of thousands of noncombatants died.

Other early camp systems included massive networks established on an emergency basis to detain immigrants or expel targeted minority groups. During the Spanish Civil War, when 475,000 refugees poured across France’s southern border in less than three weeks, many were forced into unlivable conditions in remote areas to isolate them from French society. Illness and disease followed on a massive scale.

After the start of World War II, the French government used those same camps to intern foreign Jews who had escaped Hitler’s Germany, detaining them as enemy aliens. And after France fell to the Nazis, French policemen went door-to-door in Paris in May 1941 in the service of the Vichy government to round up foreign Jews who remained at liberty. Some deported Jews were sent to barracks still holding Spanish detainees and “enemy aliens.” Camps often begin as one thing and become something else.

The relocation and detention involved in the deportation project that Trump is proposing are at least an order of magnitude greater than these debacles. The argument that a second Trump administration wouldn’t be able to launch such an operation because of a lack of personnel or legal authority should be understood as largely irrelevant because it presupposes the intention of running a precise, legal project at all.

A professional effort on this scale would be impossible. The mass deportations planned to begin in January 2025 if Trump is reelected are meant to unleash deliberate and collateral mayhem. And if history is any guide, a system of camps built to punish millions represents a threat to every American.

As for what they say they intend, Trump and his allies openly admire the results of the Eisenhower-era “Operation Wetback,” whose very name offers a slur revealing the endemic prejudice that made it possible. This limited deportation blitz led to the deaths of 88 workers in 112-degree-Fahrenheit heat. A new Trump administration would be looking to replicate that operation on a scale heretofore untried, using the largest deportation force ever seen in the U.S., according to both Trump and former director of U.S. Immigration and Customs Enforcement Tom Homan.

Trump adviser Stephen Miller has described a plan to create “vast holding facilities that would function as staging centers,” and Trump has promised to remove four percent of the current U.S. population in a deliberate plan to spur a massive disruption of the labor market. If Americans took notice of border policy during Trump’s first administration, said Homan earlier this month, “They ain’t seen shit yet.”

The “Mass Deportation Now” signs filling the audience at the Republican National Convention are a grim warning of how much worse the situation could get. Trump, his advisers, the Heritage Foundation (the extreme-right platform that has put forth Project 2025) and countless members of Congress are not only winking and nodding toward detention horrors of the past but also clearly willing to repeat history if it will let them consolidate power.

The U.S. has previously embraced concentration camps during the detention of Japanese Americans during World War II and under the family-separation policy imposed during Trump’s presidency. The broader legacy of camps on six continents offers a panoramic assortment of even more ways in which mass deportations and forced relocation can go wrong. Unleashed on anything close to the scale under discussion, the project Trump and his henchmen are proposing will be lethal to the targeted groups, catastrophic to the stability of the country and extremely difficult to undo. These camps are in no way scientific or even serious policy; they’re the equivalent of dropping a hydrogen bomb to put out a forest fire.

This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.