US President Donald Trump's first full day in office is coming to a close.

After a lengthy and fiery campaign based around lots of "day one" promises — from deporting illegal immigrants to withdrawing from the Trans-Pacific Partnership (TPP) deal — what did he get up to?

A trip to church

First up was a prayer service at Washington National Cathedral.

Mr Trump and First Lady Melania were accompanied by the Vice President and his wife.

Mr Trump entered the cathedral holding hands with his wife, Melania, and took his place in the first pew alongside Vice President Mike Pence.

The US President smiled and nodded to those who passed him during the procession.

A visit to CIA headquarters

Sorry, this video has expired President Donald Trump visits CIA headquarters in Virginia

Next Mr Trump visited CIA headquarters in Langley, Virginia.

There he told CIA officers he had great respect for the agency, denying he had had a feud with the intelligence community.

Mr Trump was effusive with his praise, telling the officers — who came in on their time off to see him — that he loved them and had their back.

"Very, very few people could do the job you people do, and I want to just let you know that I am so behind you," he said.

"And I know, maybe sometimes you haven't gotten the backing that you've wanted and you're going to get so much backing."

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In the lead-up to his inauguration, Mr Trump had been critical of intelligence officials for their assertions about Russian election hacking and about leaks about his briefings.

He repeatedly denied that massive hacking attacks from Russia sought to influence the outcome of the 2016 by targeting his rival Hillary Clinton.

But then, in a surprise twist, his chief of staff Reince Priebus told Fox News that Mr Trump now accepted "the fact".

Mr Priebus said Mr Trump planned to order the intelligence community to make recommendations as to what should be done.

A former senior CIA official said the visit was a "good gesture", but others said it might take time to forgive and forget.

"A single visit with some nice words will not outweigh prior attacks and insults," said Paul Pillar, a former top US intelligence analyst on the Middle East.

Phone calls to world leaders

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Mr Trump also spoke to Mexico's President Enrique Pena Nieto and Canadian Prime Minister Justin Trudeau by phone during the day.

Mr Pena Nieto and Mr Trump agreed to meet in the near future, according to a statement from the Mexican President's office.

Mr Pena Nieto told Mr Trump the country wanted an open dialogue with their northern neighbours, and both leaders expressed confidence it would bring good results for both countries, the statement said.

A statement from the Canadian Prime Minister's office said Mr Trump and Mr Trudeau spoke of the "importance of the Canada-United States bilateral relationship, and discussed various areas of mutual interest".

"The Prime Minister noted the depth of the Canada-US economic relationship, with 35 states having Canada as their top export destination," it said.

Assemble national security team

Mr Trump also cleared the way for members of his national security team to take their places.

He signed legislation granting James Mattis, his pick for defence secretary, a one-time exception from federal law barring former US service members who have been out of uniform for less than seven years from holding the top Pentagon job.

Senate has confirmed James Mattis (right) to lead the Homeland Security Department. ( Reuters: Mike Segar )

The restriction is meant to preserve civilian control of the military. Mr Mattis retired from the Marine Corps in 2013.

Hours later, the Senate confirmed James Mattis, and retired General John Kelly to lead the Homeland Security Department.

Both were sworn into office by Vice President Mike Pence.

Separately, White House chief of staff Reince Priebus issued a memo aimed at freezing some new regulations and halting ones the Obama administration had started.

'Promptly' repeal Obamacare

Mr Trump has also signalled an intention to make a quick and clean break from the Obama administration.

On Friday night, he signed an executive order aimed at former President Barack Obama's health care law. The order notes that Mr Trump plans to seek the law's "prompt repeal".

It allows the Health and Human Services Department and other federal agencies to delay implementing parts of the law that might impose a "fiscal burden" on states, health care providers, families or individuals.

AP/Reuters