WASHINGTON — President Trump has directed his administration to enforce the nation’s immigration laws more aggressively, unleashing the full force of the federal government to find, arrest and deport those in the country illegally, regardless of whether they have committed serious crimes.
Documents released on Tuesday by the Department of Homeland Security revealed the broad scope of the president’s ambitions: to publicize crimes by undocumented immigrants; strip such immigrants of privacy protections; enlist local police officers as enforcers; erect new detention facilities; discourage asylum seekers; and, ultimately, speed up deportations.
The new enforcement policies put into practice language that Mr. Trump used on the campaign trail, vastly expanding the definition of “criminal aliens” and warning that such unauthorized immigrants “routinely victimize Americans,” disregard the “rule of law and pose a threat” to people in communities across the United States.
Despite those assertions in the new documents, research shows lower levels of crime among immigrants than among native-born Americans.
But taken together, the new policies are a rejection of the sometimes more restrained efforts by former Presidents Barack Obama and George W. Bush and their predecessors, who sought to balance protecting the nation’s borders with fiscal, logistical and humanitarian limits on the exercise of laws passed by Congress.
“The faithful execution of our immigration laws is best achieved by using all these statutory authorities to the greatest extent practicable,” John F. Kelly, the secretary of homeland security, wrote in one of two memorandums released on Tuesday. “Accordingly, department personnel shall make full use of these authorities.”
The immediate impact of that shift is not yet fully known. Advocates for immigrants warned on Tuesday that the new border control and enforcement directives would create an atmosphere of fear that was likely to drive those in the country illegally deeper into the shadows.
Administration officials said some of the new policies — like one seeking to send unauthorized border crossers from Central America to Mexico while they await deportation hearings — could take months to put in effect and might be limited in scope.
For now, so-called Dreamers, who were brought to the United States as young children, will not be targeted unless they commit crimes, officials said on Tuesday.
Mr. Trump has not yet said where he will get the billions of dollars needed to pay for thousands of new border control agents, a network of detention facilities to detain unauthorized immigrants and a wall along the entire southern border with Mexico.
But politically, Mr. Kelly’s actions on Tuesday serve to reinforce the president’s standing among a core constituency — those who blame unauthorized immigrants for taking jobs away from citizens, committing heinous crimes and being a financial burden on federal, state and local governments.
And because of the changes, millions of immigrants in the country illegally now face a far greater likelihood of being discovered, arrested and eventually deported.
“The message is: The immigration law is back in business,” said Mark Krikorian, the executive director of the Center for Immigration Studies, which supports restricted immigration. “That violating immigration law is no longer a secondary offense.”
Lawyers and advocates for immigrants said the new policies could still be challenged in court. Maricopa County in Arizona spent years defending its sheriff at the time, Joseph Arpaio, in federal court, where he was found to have discriminated against Latinos.
And courts in Illinois, Oregon, Pennsylvania and several other states have rejected the power given to local and state law enforcement officers to hold immigrants for up to 48 hours beyond their scheduled release from detention at the request of federal authorities under a program known as Secure Communities, which Mr. Trump is reviving.
“When you tell state and local police that their job is to do immigration enforcement,” said Omar Jadwat, director of the American Civil Liberties Union’s Immigrants’ Rights Project, “it translates into the unwarranted and illegal targeting of people because of their race, because of their language, because of the color of their skin.”
Sean Spicer, the White House press secretary, said on Tuesday that the president wanted to “take the shackles off” of the nation’s immigration enforcers. He insisted that the new policies made it clear that “the No. 1 priority is that people who pose a threat to our country are immediately dealt with.”
In fact, that was already the policy under the Obama administration, which instructed agents that undocumented immigrants convicted of serious crimes were the priority for deportation. Now, enforcement officials have been directed to seek the deportation of anyone in the country illegally.
“Under this executive order, ICE will not exempt classes or categories of removal aliens from potential enforcement,” a fact sheet released by the Department of Homeland Security said, using the acronym for Immigration and Customs Enforcement. “All of those present in violation of the immigration laws may be subject to immigration arrest, detention, and, if found removable by final order, removal from the United States.”
That includes people convicted of fraud in any official matter before a governmental agency and people who “have abused any program related to receipt of public benefits.”
The policy also expands a program that lets officials bypass due process protections such as court hearings in some deportation cases.
Under the Obama administration, the program, known as “expedited removal,” was used only when an immigrant was arrested within 100 miles of the border and had been in the country no more than 14 days. Now it will include all those who have been in the country for up to two years, no matter where they are caught.
“The administration seems to be putting its foot down as far as the gas pedal will go,” said Heidi Altman, policy director for the National Immigrant Justice Center, a Chicago-based group that offers legal services to immigrants.
In the documents released on Tuesday, the Department of Homeland Security is directed to begin the process of hiring 10,000 immigration and customs agents, expanding the number of detention facilities and creating an office within Immigration and Customs Enforcement to help families of those killed by undocumented immigrants.
The directives would also revive a program that recruits local police officers and sheriff’s deputies to help with deportation, effectively making them de facto immigration agents. The effort, called the 287(g) program, was scaled back during the Obama administration.
The program faces resistance from many states and dozens of so-called sanctuary cities, which have refused to allow their law enforcement workers to help round up undocumented individuals. In New York, Mayor Bill de Blasio in a statement on Tuesday pledged the city’s cooperation in cases involving “proven public safety threats,” but vowed that “what we will not do is turn our N.Y.P.D. officers into immigration agents.”
Under the new directives, the agency would no longer provide privacy protections to people who are not American citizens or green card holders. A policy established in the last days of the Bush administration in January 2009 provided some legal protection for information collected by the Department of Homeland Security on nonresidents.
The new policies also target unauthorized immigrants who smuggle their children into the country, as happened with Central American children seeking to reunite with parents living in the United States. Under the new directives, such parents could face deportation or prosecution for smuggling or human trafficking.
Officials said that returning Central American refugees to Mexico to await hearings would be done only in a limited fashion, and only after discussions with the government of Mexico.
Mexican officials said on Tuesday that such a move could violate Mexican law and international accords governing repatriation, and immigrants’ advocates questioned Mexico’s ability to absorb thousands of Central Americans in detention centers and shelters.