U.S. President-elect Donald Trump said late Sunday he was bringing back hardline immigration official Tom Homan to oversee the country's borders in the incoming administration.

The 78-year-old Republican tycoon has pledged to launch -- on day one of his presidency -- the largest deportation operation of undocumented immigrants in US history.

"I am pleased to announce that the Former ICE Director, and stalwart on Border Control, Tom Homan, will be joining the Trump Administration, in charge of our Nation's Borders ("The Border Czar")," Trump posted on his social network Truth Social. "I've known Tom for a long time, and there is nobody better at policing and controlling our Borders."

Homan will be in charge of "all Deportation of Illegal Aliens back to their Country of Origin", Trump added.

During his campaign, Trump repeatedly railed against undocumented immigrants, employing violent rhetoric about those who "poison the blood" of the United States.

While the U.S. government has struggled for years to manage its southern border with Mexico, Trump has super-charged concerns by claiming an "invasion" is underway by migrants he says will rape and murder Americans.

In rally speeches, he wildly exaggerated local tensions and misled his audiences about immigration statistics and policy.

Violent crime, which spiked under Trump, has fallen in every year of President Joe Biden's administration.

Migrants commit fewer crimes proportionately than the native population, though foreign suspects have been named in a few high-profile cases of violent attacks on women and children, infuriating Republicans.

The number of U.S. border patrol encounters with migrants crossing over from Mexico illegally is now about the same as in 2020, the last year of Trump's presidency, after peaking at a record 250,000 for the month of December 2023.

Trump vowed to tackle migrant gangs using the Alien Enemies Act of 1798 -- which allows the federal government to round up and deport foreigners belonging to enemy countries -- as part of a mass deportation drive he christened "Operation Aurora."

Aurora was the scene of a viral video showing armed Latinos rampaging through an apartment block that spurred sweeping, false narratives about the town being terrorised by Latin American migrants.

Trump has similarly promoted the fictitious story that Haitian migrants in Springfield, Ohio, are eating residents' pets.