Donald Trump will be sworn in as US president soon, ushering in another turbulent four-year term with promises to push the limits of executive power, deport millions of immigrants, secure retribution against his political enemies and transform the role of the US on the world stage.

Even before Trump was to take office at noon ET (1700 GMT), aides detailed a raft of executive actions that he will sign immediately, including 10 focused on border security and immigration, his top priority.

The president will declare a national emergency at the southern border, send armed troops to the region and reimpose a policy forcing asylum seekers to wait in Mexico for their US court dates, an incoming White House official told reporters.

The inauguration completes a triumphant comeback for a political disruptor who survived two impeachment trials, a felony conviction, two assassination attempts and an indictment for attempting to overturn his 2020 election loss.

The ceremony will take place inside the Rotunda of the US Capitol, four years after a mob of Trump supporters breached the symbol of American democracy in an unsuccessful effort to forestall the Republican Trump's defeat to Democrat Joe Biden. The swearing-in was moved indoors for the first time in 40 years due to the extreme cold. 

Trump, the first US president since the 19th century to win a second term after losing the White House, has said he will pardon "on Day One" many of the more than 1,500 people charged in connection with the Jan. 6, 2021, attack. Biden, in one of his last acts, pardoned lawmakers and congressional staff who investigated the riot, along with police officers who testified.

That promise is among a flurry of executive actions Trump intends to sign as soon as Monday after taking the oath of office.

Trump will restore the federal death penalty, which Biden had suspended, and require that official US documents such as passports reflect citizens' gender as assigned at birth, incoming administration officials told reporters.

He will also sign an order ending diversity, equity and inclusion initiatives in the federal government on his first day, which is also Martin Luther King Jr. Day, the officials said.