Donald Trump vowed to usher in a new era of American greatness, minutes after he was sworn in as president for the second time to complete an extraordinary political comeback.
"The golden age of America begins right now," he said.
Trump took the oath of office to "preserve, protect and defend" the US Constitution at 12:01 p.m. ET (1701 GMT) inside the US Capitol, administered by Chief Justice John Roberts. His vice president, JD Vance, was sworn in just before him.
Trump intends to sign a raft of executive actions in his first hours as president, incoming White House officials said on Monday, 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 there and resume a policy forcing asylum seekers to wait in Mexico for their US court dates, officials told reporters.
He will also seek to end so-called birthright citizenship for US-born children whose parents lack legal status, a move some legal scholars have said would be unconstitutional.
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 was moved inside the Capitol due to the extreme cold, four years after a mob of Trump supporters breached the building, a symbol of American democracy, in an unsuccessful effort to forestall Trump's loss to Joe Biden.