Donald Trump has declared that the “golden age of America begins right now” as he was sworn in as the 47th US president on Tuesday morning (AEDT).

Trump, 78, stood with his hand on a Bible and took the oath of office at the inauguration ceremony, which was held indoors to escape the bitter cold outside on Capitol Hill.

In his speech, Trump vowed to immediately sign a raft of executive actions, while taking a swipe at the outgoing administration by stating that “America’s decline is over”.

“We are on the verge of the four greatest years in American history,” he said.

“The future is ours and our golden age has just begun.”

Trump said his journey to “reclaim our republic” — and take office for a second time — had not been easy, referring to the court cases against him and the attempts on his life.

“I was saved by God to make America great again,” he said.

First among Trump’s priorities, he vowed to declare a ‘national emergency’ at the US’s southern border and “return millions of illegal aliens” under his “Remain in Mexico” policy.

This would include ending the practice of “catch and release”, he said, and sending down troops to repel the “disastrous invasion of our country”.

Drug cartels would be declared as “foreign terrorist organisations” and foreign criminal gangs within America would be “eliminated”, he promised.

Next, Trump said he would “defeat record inflation” and “rapidly bring down costs and prices”.

“The inflation crisis was caused by massive overspending and escalating energy prices and that is why today I will also declare a ‘national energy emergency’,” he said.

Trump said the US was going to “drill, baby, drill” its oil and gas reserves — “the liquid gold under our feet” — and “export it all over the world”.

Mandates on electric vehicles would be revoked and the US would start buildings cars “at a rate that no one would have thought possible”, said Trump.

On the issue of tariffs, which has made international economies nervous, Trump said he would make Americans wealthy by taxing others.

An External Revenue Service would be established to collect the “massive amounts of money” that would be “pouring in” from foreign sources.

On gender, Trump said he would sign an order declaring only two sexes — male and female.

The Gulf of Mexico would be renamed the Gulf of America and he said the highest mountain in America, Denali, would be restored to its earlier name Mount McKinley, after the 25th US president.

Trump said the US would be “taking back” the Panama Canal and would planting the national flag on the planet Mars.

“China is operating the Panama Canal and we didn’t give it to China, we gave it to Panama and we’re taking it back,” he said.

The speech also echoed many of the themes Trump’s sounded at his first inauguration in 2017 when he spoke darkly of the “American carnage” of crime and job loss that he said had ravaged the US.

But he said his “proudest legacy” would be that of a “peacemaker and unifier”.

“We will again build the strongest military the world has ever seen,” he said.

“We will measure our success not only by the battles we win, but also by the wars that we end, and perhaps most importantly, the wars we never get into.”

Afterwards, he addressed his supporters in a long and rambling speech that was more vintage Trump, attacking his adversaries such as former Republican congresswoman Liz Cheney, who he called a “crying lunatic”, and boasting about his voting numbers.

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.

Incoming administration officials said Trump would sign an order ending diversity, equity and inclusion initiatives in the federal government on Monday (local time). The day is also Martin Luther King Jr Day, a holiday in memory of America’s most famous civil rights leader.

But Trump will not immediately impose new tariffs on Monday, instead directing federal agencies to evaluate trade relationships with Canada, China and Mexico, an official said.

Outgoing president Joe Biden and his vice-president Kamala Harris, who lost to Trump in November, were inside the Capitol’s Rotunda, along with former presidents Barack Obama, George W Bush and Bill Clinton, for the ceremony.

Former secretary of state Hillary Clinton, who lost to Trump in 2016, arrived with her husband Bill. Obama’s wife Michelle chose not to attend.

Shortly before 10am, Trump and incoming first lady Melania Trump arrived at the White House, where Biden and wife Jill greeted them with handshakes.

“Welcome home,” Biden said.

Shortly before leaving the White House, Biden posted a photograph of himself and his wife.

“One more selfie for the road. We love you, America,” he wrote on the platform X on Monday morning.

The photo shows Biden, 82, and Jill, 73, beaming against the backdrop of a snowy garden at the White House.

-with DPA/AAP