Newly installed President Donald Trump has moved swiftly to turn his fiercely nationalist "America first" inaugural speech into action, stoking unease abroad over the new direction the United States is headed under his leadership.

On Day One of his presidency, the White House moved to withdraw the United States from the Trans-Pacific Partnership trade pact. The Obama administration's signature domestic programme, the Affordable Care Act, also fell victim to Mr Trump's move to unpick his predecessor's policies.

In his fiery inauguration address on Friday, Mr Trump painted a bleak picture of America today - one exploited by foreign countries, burdened with lopsided alliances and failing to defend its borders.

"For many decades, we've enriched foreign industry at the expense of American industry; subsidised the armies of other countries, while allowing for the very sad depletion of our military," he said, blasting past policies.

"One by one, the factories shuttered and left our shores, with not even a thought about the millions and millions of American workers that were left behind."

WHAT AMERICA NEEDS We must protect our borders from the ravages of other countries making our products, stealing our companies and destroying our jobs. Protection will lead to great prosperity and strength. US PRESIDENT DONALD TRUMP, on why he is choosing to go down the protectionist route.

What's left behind, he said, is a dystopia of blighted inner cities and rusted-out factories "scattered like tombstones" across the land.

"This American carnage stops right here and stops right now," Mr Trump declared.

"From this day forward, it's going to be only America first... Every decision on trade, on taxes, on immigration, on foreign affairs will be made to benefit American workers and American families."

Mr Trump, revisiting the election campaign themes that resonated strongly with what he called the "forgotten" voters of Middle America, made clear that under his administration, the US will be hard-nosed in protecting its own interests.

"We must protect our borders from the ravages of other countries making our products, stealing our companies and destroying our jobs," he said.

Mr Trump's signalling of a dramatic shift in policy has set off ripples of concern in world capitals, even as congratulations and offers to improve ties flooded in.

The premiers of Japan and Britain plan to meet Mr Trump in the coming weeks. While Prime Minister Shinzo Abe yesterday reiterated the importance of US-Japan ties, Mr Masahiko Komura, vice-president of Japan's ruling Liberal Democratic Party, was quoted in the Mainichi Shimbun as saying: "If each country begins focusing only on itself, the economic state of the world - including the US - will be disastrous."

Although Beijing has yet to issue an official response to Mr Trump's inaugural address, a commentary in the official Xinhua news agency noted that "cooperation also demands reciprocal flexibility instead of a beggar-thy-neighbour mentality".

In Germany, Chancellor Angela Merkel yesterday acknowledged that there were differences of opinion but said that she would work to arrive at compromises with Mr Trump on issues like trade and military spending.

After his hard-hitting opening speech as President, Mr Trump switched to glitzier engagements in the evening, with a series of inaugural balls followed by a prayer service at the National Cathedral the next day.

He is expected to push ahead with more policy changes this week.

Meanwhile, he continues to be dogged by protests at home and abroad.

Yesterday, after protests in Australia, New Zealand and parts of Asia, thousands of demonstrators gathered for a massive Women's March in Washington, to highlight racial and gender equality and other issues deemed to be in jeopardy under the new Trump administration.

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