So how WILL Trump deport 20 million? It's the bold pledge that helped propel him back into the White House. Now our US Editor reveals his $1trillion 'shock and awe' blueprint...

When Donald Trump is inaugurated as America's 47th president on January 20, the event will mark the official start of his second term in office with carefully stage-managed images that will be seen around the world.

Within hours of the event, Trump will take his seat behind the Resolute desk in the Oval Office and launch what he calls 'the biggest mass deportation in American history'.

While the expulsion of illegal immigrants was a focal point of Trump's election campaign, the precise details of how he intends to accomplish his goal of removing as many as 20 million people from US soil have largely remained unknown.

Until now.

The Mail on Sunday has spoken to those in Trump's inner circle who say his immigration plans have been top of the list in discussions held at Mar-a-Lago, his Florida home, in the days since his crushing victory.

One lawyer familiar with the talks told me: 'Donald is preparing for a series of moves against illegal immigrants, which he says will cause 'shock and awe'. Kicking out illegals was the mainstay of his run for the White House and he knows people expect action on Day One. They will get it.'

The source claims Trump will immediately sign a series of executive orders, the most radical of which will be to close the border. 

Citing an immigration crisis, he will temporarily shut the southern border to give officials a chance to clear a huge backlog of cases. 

Trump claims that the Joe Biden administration allowed more than 10 million people to illegally enter the US, bringing the total number of illegal immigrants to 20 million.

There are plans to significantly increase the number of armed officers on horseback patrolling the rugged terrain close to the US's border with Mexico. 

And, of course, construction will resume on the infamous wall running between the two countries, which was a central – if unfulfilled – plank of Trump's immigration policy during his first term. 

Having lengthened the wall to around 700 miles (of the near 2,000-mile border), work abruptly stopped when Biden came to power. Trump has vowed to complete the $8 billion job by inviting businesses to 'sponsor' sections.

'Step One' of the deportation programme is to target undocumented immigrants with ties to criminal gangs. 

It is dubbed 'Operation Aurora', after the Colorado town where members of the ruthless Venezuelan street gang Tren de Aragua turned apartment complexes into bases for drug dealing and prostitution.

Trump plans to invoke the Alien Enemies Act of 1798, which gives presidents the authority to detain and deport non-citizens from 'hostile nations' during times of war and conflict. The law was used to justify the building of Japanese internment camps during the Second World War.

According to those familiar with Trump's plans, he will target the 700,000 Venezuelans, Haitians, Cubans and Nicaraguans he has branded 'vicious criminals from countries that hate us', who have been allowed to stay in the US under a Biden parole programme.

And what if, as is highly likely, countries refuse to take back violent gang members? Trump will cut off aid and ban travellers from those countries from entering the US, even on tourist visas.

'Step Two' is to expel more than one million people whose applications to remain in the US have been denied and who are on the deportation list.

Then the round-up of the millions of remaining illegal immigrants will begin as part of 'Step Three'. Places of work, including farms and meatpacking plants, will be subject to raids (or 'targeted enforcement activities') – something the American Civil Liberties Union calls 'vile, unconstitutional and un-American'.

Individuals will be taken to 'holding centres' before their deportation is fast-tracked.

Experts say the cost of the first two steps could be as much as $300 billion and the cost of expelling every illegal alien – something even Trump privately admits is impossible – could be as much as $1 trillion.

The MoS understands Trump is considering deploying the military and National Guard to build 'tent cities' on unused federal land, including property belonging to schools and prisons.

He will reintroduce the 'Remain in Mexico' Act, which will compel potential immigrants – mostly from Central and South America but increasingly from China and Eastern Europe – to stay on the southern side of the border while their visa applications are processed.

Ronald Vitiello was director of Immigration and Customs Enforcement (ICE) during Trump's first term in office. His predecessor was Tom Homan, the man now anointed by Trump as his 'Border Czar'.

Mr Vitiello told the MoS: 'We wouldn't be contemplating removing 20 million people if they [the Democrats] didn't let them all in. It's a travesty we're in this situation and it's completely preventable.

'Enforcement is difficult, expensive and risky for frontline operatives, but very necessary.

'The ICE is going to have to find people who don't want to be found, plan safe arrest and custody, find a place for them to stay, have due process in court, and the logistics to send them home.' So how exactly will it work?

Trump is said to be planning to merge ICE and Border Patrol – the federal law enforcement agency – into one 'uber' organisation of 88,000 people and will release millions in central funding to add 40,000 new agents and 8,000 extra immigration court judges to expedite expulsions.

Ira Mehlman, from the Federation for American Immigration Reform (FAIR), is reportedly advising the incoming Trump administration. 

He said last night: 'There are about 647,000 people with criminal records who have been allowed into the United States. Of those, 435,000 have convictions, including 13,000 murderers. Nobody's going to miss them if they're sent home.'

But how will authorities find those who don't want to be found?

'It's like finding any criminal,' a law enforcement source told me. 'You target their homes, the people who are financially supporting them. These people are not rocket scientists. If you put pressure on their families to give them up, nine times out of ten it works.'

Mehlman defended raids on businesses saying: 'The Government will go after employers who hire illegal immigrants. They have business licences and assets. You go in there, you bust the employers for violating the laws and you send a very clear message.

'Their competitor down the street, who might be doing the same thing, might then think, 'I don't want to risk this,' and will stop hiring illegal immigrants.'

But it is the rounding up of the bulk of migrants under 'Step Three' that will likely produce the defining images of Trump's second term.

Many of these people will have children, after being in the US for years. Pictures of families being torn apart, of children being ripped from their parents' arms, could backfire on Trump.

But the lawyer who has been speaking to Trump's team says: 'What you have to remember is that President Obama deported five million people, and no one talks about that because he's a Democrat.'

It was under Obama, he observes, that controversial chain-link fence enclosures – or cages – in deportation holding centres were first built. 'President Trump has a professional team around him,' says the lawyer. 'The best of the best. They have been working on this immigration plan for years.'

And, crucially, Trump 'has the mandate of the people'.

He insists that the President-elect isn't against immigration, pointing out that Trump is married to Melania, a Slovenian-American; his first wife Ivana was born in what was then Czechoslovakia; and Elon Musk, 'his best buddy', hails from South Africa. 

'He wants to make the American Dream achievable again, but only for people who have the legal right to be here,' he says.

Intriguingly, Trump is exploring paying 'third-party safe countries' to take non-violent applicants while their visas are being processed. The scheme is similar to Rishi Sunak's now abandoned Rwanda plan, in which migrants who crossed the Channel illegally were to be flown to Rwanda to seek asylum there instead.

The source said: 'Trump isn't a monster. He understands many asylum seekers may face death if they have to return to their country of origin. There will be safe third-party countries which will house these people at some cost to the US taxpayers. But they will be the exception, not the rule.'

Alfonso Aguilar, former chief of the US Office of Citizenship under President George W. Bush, told the MoS: 'The biggest challenge will be communicating the immigration policy to the American people before the Democrats cry that it's a humanitarian crisis or cruel and inhumane. The Trump administration will need to show that this is a fair and just process.'

The American Civil Liberties Union has amassed a team of lawyers to fight deportations, while California governor Gavin Newsom says public defenders will be available to all illegal immigrants 'to ensure they get a fair trial'.

But Trump will try to bypass existing human rights laws and introduce 'deport now, ask questions later' legislation, and he has the numbers to do so given his party's control of the Senate and House of Representatives.

Furthermore, legal challenges will ultimately end up in the Supreme Court, which is currently weighted in Trump's favour.

No doubt the deportation plan will present a bumper payday for lawyers, but construction and transport companies will benefit, too. While the intention is to use federal housing, the military and border agents, the sheer size of the job means it is likely the Government will hire contractors to build temporary housing and provide extra planes for transportation. 

Tellingly, within 24 hours of Trump's decisive victory on November 6, shares in 'private prison' firms such as CoreCivic and Geo Group surged.

Many fear Trump's plans could severely damage the US economy, often citing the example of Florida where governor Ron DeSantis issued the country's most stringent anti-illegal immigration orders 18 months ago.

Today, farmers in the state complain they do not have enough people to pick Florida's trademark oranges, while small business owners say they are being forced to shut down because Americans don't want to do menial jobs.

One restaurant owner who gave his name only as 'Charles' said: 'It's tough to find people to wash dishes. American students don't want to do this.

'If Trump gets rid of everyone doing the dirtiest jobs, then who will do them?'

'There may be shortages at first, some holes in the system,' concedes the lawyer close to Trump. 'But most illegal immigrants come here because they want to work, they want to create a better life for their families. All we are saying is, do it properly.'

Whether businesses that rely on imported labour will see it in such simple terms remains to be seen, as does the strength of protest from the blue half of America that voted Democrat. 

What is more certain is that the success or otherwise of Trump's plan to deport some 20 million people will determine the fate of his second term.

Additional reporting by Peter Sheridan