WASHINGTON — Immigration and Customs Enforcement in recent days has bulked up the branch responsible for carrying out deportations in preparation for the mass arrests of undocumented immigrants, two Department of Homeland Security officials said on Tuesday, adding that the agency could not immediately deport “millions of illegal aliens” as President Trump had promised the night before.
Senior ICE officials, many of whom were blindsided by Mr. Trump’s tweet, have signaled for weeks that the agency would conduct raids targeting thousands of migrant families in homes and communities, something one of the homeland security officials confirmed on Tuesday was expected in the coming weeks.
ICE has requested that agents in Homeland Security Investigations — the branch of the agency that conducts long-term investigations into human trafficking and drug smuggling — assist Enforcement and Removal Operations, which deports undocumented immigrants, according to the two homeland security officials. They said the nationwide reallocation of resources was rare and a sign that ICE would soon conduct mass arrests.
But agents were not clear what specifically Mr. Trump was referring to in his tweet on Monday, which came less than 24 hours before he was scheduled to appear in Florida for a rally to kick off his 2020 re-election campaign.
On Tuesday afternoon, Mr. Trump repeated that immigration officials planned to conduct a deportation operation next week. “They know. They know,” Mr. Trump said as he left for Florida. “They’re going to start next week and when people come into our country and they come in illegally, they’ll have to go out.”
But immigration laws prevent the Trump administration from immediately deporting asylum-seeking Central American families, who make up a majority of the migrants arrested at the border. The operation planned by ICE officials would instead target those in the interior of the country who have been issued a final removal order or missed their court date.
A president releasing the timeline of such raids would be unprecedented because it could spread panic in communities and potentially threaten the success of the raids. An operation targeting families also would not immediately result in the deportation of millions of undocumented immigrants, according to officials who were not authorized to speak publicly about the details of the coming operation or Mr. Trump’s tweet.
ICE charters planes that carry only a couple of hundred migrants back to Central America daily.
While roughly a million undocumented immigrants have been issued removal orders, many of them may be appealing their cases and cannot be deported. The roughly 6,000 deportation officers in ICE also do not know the locations of many of the migrants.
Last fiscal year, Enforcement and Removal Operations deported more than 250,000 undocumented immigrants. Under President Barack Obama, whom critics nicknamed the “deporter in chief” for aggressively sending home criminals and recent border-crossers, the annual number of deportations peaked in 2012 at about 410,000.
ICE officials have changed their minds multiple times in recent days about when to begin the operation to target families, according to one of the homeland security officials. The agency has long been hesitant about such raids because of the bad optics they generate.
On Tuesday afternoon, ICE released a statement saying it was committed to enforcing immigration law, including “routine targeted enforcement operations, criminals, individuals subject to removal orders and work site enforcement.”
This month, in his first extensive comments with reporters as ICE’s acting director, Mark Morgan told reporters that the agency would increase efforts to deport migrants who missed a court hearing or otherwise received a deportation order.
He specified that this would include families, a sign that the agency was preparing to give in to White House pressure to raid migrant families’ homes and neighborhoods.
While ICE officials argue that undocumented adults who have been given a final order of removal should be deported quickly, the idea of rounding up and deporting those who have children in the United States has been fraught for years, even before Mr. Trump took office. Many families include an undocumented parent and a child who is a citizen of the United States and cannot be deported.
Ronald D. Vitiello, ICE’s former acting director, had warned that such an operation would generate public outrage. Mr. Trump pulled Mr. Vitiello’s nomination in April, saying he wanted the agency to go in a “tougher direction.”
The concern among law enforcement officials about backlash was heightened after last summer’s decision by the Trump administration to separate migrant families at the border. The images of the crying children and distraught parents ultimately forced Mr. Trump to back off the policy.
Widespread raids of families could provoke a similar outcry, much of it directed against the gun-wielding agents making the arrests. That has left homeland security’s leadership nervous about the potential consequences of the operation.
For Mr. Trump, the threat of imminent mass deportations is a stark reminder that he intends to seek re-election by doubling down on the central campaign theme that propelled him to the White House in 2016 — stoking fear of immigrants.
But Mr. Trump has largely failed to make good on his immigration promises. His demand for a wall along the southwestern border has been denied by Congress, and courts have blocked some of his more aggressive efforts to deny entry to migrants.
That has enraged Mr. Trump, who has at times come under fire from conservative activists and television hosts for not living up to his promises. His vaguely worded tweet on Monday night appeared to be intended to reassure his supporters that his plans for deporting undocumented immigrants are on track.