Riots are continuing to erupt throughout Washington in anti-Trump protests just blocks away from where the inaugural parade is set to take place.
Violent protesters have clashed with police and brought traffic to a standstill in the capital.
Around 100 people were arrested by 3pm local time (8pm GMT) and police fired tear gas and concussion grenades to quell the protesters.
Jobs for Americans, a strengthened military, new trade deals and support for police will shape Donald Trump's four years in government.Read the full story ›
Donald Trump pledged to put "America first" as he addressed the nation after being sworn in as the 45th president of the United States.Read the full story ›
"Numerous" arrests have been made in Washington after violent protests erupted during Donald Trump's inauguration, with some charged with rioting.
Police said pepper spray and "other control devices" were used to "control the criminal actors" and "protect persons and property".
Two officers sustained minor injuries from "coordinated attacks" and police vehicles were damaged, the city's police department added.
Donald Trump vowed to put "America first" as he set out a nationalist agenda after being sworn in as the 45th president of the US.Read the full story ›
President Trump has arrived at the Inaugural Luncheon, where he will have his first meal as President of the United States.
It often features cuisine that reflects the home states of the new President and Vice President.
There will also be speeches, gift presentations and toasts to the new administration.
Boris Johnson offered his "warmest congratulations" to Donald Trump, after the billionaire was sworn in to "the most important political office in the world".
In a video posted on his Facebook page, the Foreign Secretary said: "I know that billions of people will be willing him to succeed in the months and years ahead in the very great challenges that he faces.
"We in the United Kingdom will work hand in glove for the stability, the prosperity and the security of the world with President Donald Trump."
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Donald Trump has signed paperwork making his presidency official.
He signed his first executive orders, formal nominations and a proclamation for a national day of patriotism.
The US President also signed a measure granting Mattis Waiver to serve as Defence Secretary.
Supporters of Donald Trump watched on in Washington as the Republican was officially sworn in as President.
Tens of thousands of the new President's fans were seen bearing Trump flags, banners and memorabilia.
Donald Trump's first speech as President of the United States was "probably the most nationalist speech we've heard from any western leader in modern times," ITV News Political Editor Robert Peston said.
Mr Trump's opening address to the American people was in stark contrast to Theresa May's Brexit speech on Tuesday, which was "one of the most internationalist" speeches from a British prime minister, he said.
He continued: "It just shows you the great gulf in vision between Theresa May and Donald Trump.
"Donald's Trump's stress on putting America first - and he particularly referred to trade - does suggest that when that trade deal is negotiated, frankly, the dividends for the UK may not be that great."