Donald Trump sworn in as 45th US president, vows to put ``America First`` and eradicate `radical Islamic terrorism`

In an inaugural address that was a populist, anti-Washington rallying cry, Donald Trump vowed to pursue `America First` policies.

Washington: Donald Trump was sworn in as the 45th President of the United States on Friday, taking the oath of office at the US Capitol as hundreds of thousands of jubilant supporters cheered the historic handover of power.

In an inaugural address that was a populist, anti-Washington rallying cry, Trump vowed to pursue "America First" policies.

The 70-year-old Republican placed his hand on two Bibles -- his own and one used by Abraham Lincoln -- to take the solemn oath, ushering in a new political era that has been met with delight and dread in equal measure.

"I, Donald John Trump, do solemnly swear that I will faithfully execute the office of president of the United States, and will to the best of my ability, preserve, protect and defend the Constitution of the United States. So help me God," he declared, before pumping his fist in the air several times.

Sketching a bleak vision of a country he said was ravaged by rusted-out factories, crime, gangs, and drugs, Trump indirectly blamed his predecessors in the White House for policies that helped the establishment at the expense of struggling families.

"From this moment on, it`s going to be America First," the Republican told hundreds of thousands of people gathered on the grounds of the National Mall after taking the oath of office on the West Front of the US Capitol.

Four past US presidents, three Democrats, and a Republican sat nearby. Scattered street protests erupted against Trump elsewhere in Washington.

Missed Donald Trump`s inaugural address? Read full text here

In his address, Trump sought friendship with the nations of the world but made it clear that the US will do so with the understanding that it is the right of all nations to put their own interests first.

"We do not seek to impose our way of life on anyone, but rather to let it shine as an example. We will shine for everyone to follow," he said in an optimistic and visionary inaugural speech that lasted for over 16 minutes.

Continuing with one of his election campaign themes, Trump said that for many decades, Americans have enriched foreign industry at the expense of the American one.

"Subsidized the armies of other countries while allowing for the very sad depletion of our military. We've defended other nation`s borders while refusing to defend our own; and spent trillions of dollars overseas while America's infrastructure has fallen into disrepair and decay," he said.

"We`ve made other countries rich while the wealth, strength, and confidence of our country has disappeared over the horizon. One by one, the factories shuttered and left our shores, with not even a thought about the millions upon millions of American workers left behind," he added.

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And the wealth of the middle class has been ripped from their homes and then redistributed across the entire world.

"But that is the past. And now we are looking only to the future. We assembled here today are issuing a new decree to be heard in every city, in every foreign capital, and in every hall of power," Trump said.

"From this day forward, a new vision will govern our land. From this moment on, it`s going to be America First. Every decision on trade, on taxes, on immigration, on foreign affairs, will be made to benefit American workers and American families," he said.

Under pressure to unite the country after the bitterly fought campaign, Trump said that through allegiance to the United States, "we will rediscover our loyalty to each other" and called for a "new national pride" that would help heal divisions.

Abroad, Trump signalled the possibility of a more aggressive approach to Islamic State militants than his immediate predecessor, Democrat Barack Obama.

"We will reinforce old alliances and form new ones, and united the civilized world against radical Islamic terrorism, which we will eradicate completely from the face of the earth," he said.

Vowing to fight for American interests, Trump said: "I will fight for you with every breath in my body, and I will never, ever let you down. America will start winning again, winning like never before."

"We will bring back our jobs. We will bring back our borders. We will bring back our wealth. And we will bring back our dreams," he said.

After repeating the 35-word oath of office, Trump stretched his arms wide and hugged his wife, Melania, and other members of his family. Ceremonial cannon blasts fired.

Earlier, Mike Pence was sworn in as US Vice President.

The transition from a Democratic president to a Republican took place before a crowd of former presidents, dignitaries and hundreds of thousands of people on the grounds of the National Mall. The crowd stretched westward on a cool day of occasional light rain.

Away from the Capitol, masked activists ran through the streets smashing windows with hammers at a McDonald’s restaurant, a Starbucks coffee shop and a steakhouse several blocks from the White House.

They carried black anarchist flags and signs that said, "Join the resistance, fight back now." Police used pepper spray and chased them down a major avenue.

In another location not far from the White House, protesters also scuffled with police, at one point throwing aluminum chairs at them at outdoor café.

Former presidents George W Bush and Jimmy Carter were present at the inauguration with their wives. Bush`s father, former president George HW Bush, 92, was in Houston recovering from pneumonia. The inauguration ceremony was also attended by Hillary Clinton and her husband, former president Bill Clinton.

Trump and his vice president, Mike Pence, began the day with a prayer service at St John`s Episcopal Church near the White House.

Trump took office with work to do to bolster his image.

(With Agency inputs)