Former President Donald Trump has vowed, if elected, to lead a large-scale deportation operation that some immigration and military experts agree is theoretically possible but problematic and could cost tens — even hundreds — of billions a year.

In fiscal year 2023, Immigration and Customs Enforcement (ICE) officers made 170,590 administrative arrests, a 19.5 percent increase over the previous year and more than any year of the Trump presidency.

If he wins a second term, Trump has promised to exponentially increase this activity and has suggested deporting all 11 million people living in this country without legal immigration status.

His team has, at various times, suggested starting with “criminals,” though they’ve offered few details on who they’d prioritize.

One cost estimate: $88 billion – $315 billion per year

A new report from the American Immigration Council, an immigration rights research and policy firm, estimates that deporting even one million undocumented immigrants a year would cost more than $88 billion annually, for a total of 967, 9 billion dollars over more than ten years.

The report acknowledges that there are significant cost variables depending on how such an operation would be carried out, and says its estimate does not take into account the loss of tax revenue from workers, nor the greater economic loss if people self-deport and American companies are losing their workforce.

A one-time effort to deport even more people in one year could cost about $315 billion annually, the report estimates, including about $167 billion for mass immigration detention.

SEE ALSO: What happens to Trump’s criminal cases if he wins the election — or loses?

According to the group, the two biggest costs would be hiring additional staff to conduct deportation raids and building and staffing mass detention centers. “There would be no way to accomplish this mission without mass detention as an intermediate step,” the report said.

The Trump campaign official agrees that one of the biggest logistical hurdles in any mass deportation effort would be building and staffing new detention centers as a stopgap solution.

Stephen Miller, a senior Trump adviser, has said repeatedly that if Trump wins the White House, his team plans to build facilities to house 50,000 to 70,000 people. By comparison, the entire US jail and prison population in 2022, including every person held in local, county, state, and federal jails and prisons, is currently 1.9 million people.

The American Immigration Council report estimates that deporting one million immigrants a year would require the United States to “build and maintain 24 times more ICE detention capacity than currently exists.”

There are currently an estimated 1.1 million undocumented immigrants in the country who have received “final orders of removal.” Those individuals, in theory, could be immediately removed by ICE agents, but due to limited resources ICE agents have recently focused on those individuals who have recently arrived or who have dangerous crimes.

“I think it’s possible that they could execute this. Human resources would be the hardest thing for them to overcome. They would have to pull ICE agents from the border if they want to go to the cities,” Katie Tobin, a researcher at the Carnegie Endowment for International Peace, who was President Joe Biden’s top immigration adviser on the National Security Council, told ABC News.

ICE agents currently assist Customs and Border Patrol agents at the border by conducting expedited deportations of new arrivals who have recently entered the country illegally and provide logistical support to the Department of Homeland Security.

A new mandate to round up and deport people who have been living in the country for some time could mark a significant change for the law enforcement agency.

The American Immigration Council report estimates that to carry out even one million deportations a year, ICE would need to hire about 30,000 new officers, “instantly making it the largest law enforcement agency in the federal government,” it said in the report.

Trump Campaign: Deportation Costs Less Than Migrants

Trump’s campaign argued that the cost of deportation “pales in comparison” to other costs associated with housing and providing social services to recent migrants. “Kamala’s border invasion is unsustainable and is already destroying the fabric of our society. Mass deportations of criminal illegal immigrants and the restoration of an orderly immigration system are the only way to solve this crisis,” Karoline Leavitt, national press secretary for the Trump campaign. , told ABC News in a statement.

Trump has promised to mobilize and federalize National Guard units to help with the deportation effort, which would likely be a first for the military.

Under US law, military units are prohibited from engaging in domestic law enforcement, although Trump has proposed invoking the Insurrection Act, a sweeping law that could give him broader powers to direct National Guard units as he sees fit.

“We don’t like the uniformed military in our domestic affairs at all,” William Banks, a Syracuse University professor and founding director of the Institute for National Security and Counterterrorism, told ABC News in a telephone interview. “The default is always for civilians to do it. The cops, the state police, the city police, the sheriffs,” he continued.

Using the military for domestic law enforcement would be a fundamental change, one that Banks argues too few Americans have considered or faced.

“It would turn the whole society upside down … all these arguments about him being an autocrat or a dictator, it’s not a stretch,” he said. For example, uniformed military officers are not trained in law enforcement and if they were asked to make civilian arrests there could be conflicts and significant violations of civil liberties.

To target and deport immigrants who have “final orders of removal” but whose cases are still pending, Trump has discussed using another rare legal maneuver to give himself broad authority to target and detain immigrants without a hearing, formally invoking especially the foreigner. Enemies Act of 1798, a wartime law last used during World War II to detain Japanese Americans.

Trump would also require other nations to accept deportees and allow deportation flights to land back on their soil.

Katie Tobin, a researcher at the Carnegie Endowment for International Peace who served as President Joe Biden’s top immigration adviser on the National Security Council, told ABC News: “Last time, the Trump administration didn’t hesitate to threaten with punitive actions against countries that don’t cooperate with them on immigration, but there are some practical issues there in terms of how many flights a country like Guatemala or Colombia can accept per week.”

There would likely be less tangible and more indirect costs of a mass deportation effort. Inevitably, there would be ripple effects throughout the economy. In 2022 alone, undocumented immigrant households paid $46.8 billion in federal taxes and $29.3 billion in state and local taxes, according to the report, and “undocumented immigrants also contributed 22 .6 billion to Social Security and $5.7 billion to Medicare”.

The human balance sheet

Experts also predict that if a future Trump administration were to follow through with a large, initial and highly visible deportation operation, a significant number of individuals and families would likely choose to self-deport to avoid family separations or having to spend time in a military-style detention center.

The authors of the American Immigration Council report argue that the effect of a mass deportation program as described by Trump and his advisers would “almost certainly threaten the well-being” of even those immigrants with legal status in the United States and “even, potentially, citizens naturalized Americans and their communities.”

“They would live under the shadow of gun law enforcement while the US goes after their neighbors and, as social scientists have discovered under the Trump administration, they would be prone to worry that they and their children could be next “, the report says.

In recent interviews and conversations with reporters, Trump’s fellow Ohio Sen. JD Vance sidestepped the question of whether a future Trump administration would separate families during a new deportation effort or in detention centers along the border.

“If a guy commits gun violence and goes to jail, that’s family separation, which of course is tragic for the kids, but you have to prosecute the offenders and you have to enforce the law,” Vance told reporters in September while visiting the border .