Donald Trump used his first full working day in the White House to launch a bonfire of 'red tape' and government waste, pull America out of a major trade deal, and cut funding for abortion.
On what his team called "Day One" of his administration, Mr Trump vowed to cut back regulations "by 75pc, maybe more", and banned his government from hiring any more people unless they were for the military.
"There's been a lack of respect for taxpayers' money in this town for too long. We have got to respect taxpayers' money," said his spokesman, Sean Spicer.
In the Oval Office, Mr Trump signed an executive order formally withdrawing the US from the proposed Trans-Pacific Partnership, an agreement with 11 Pacific Rim countries that was backed by president Barack Obama as part of his "pivot" to strengthen ties with Asia.
After signing, Mr Trump said: "Great thing for the American worker that we just did."
He also reinstated the so-called Mexico City Policy, a ban on giving taxpayers' money to international groups that perform or provide information on abortions. Mr Obama had rescinded the ban in 2009.
The president announced his son-in-law and key adviser, Jared Kushner, would meet with Canada's prime minister, Justin Trudeau, in the run-up to an effort to renegotiate the North Atlantic Free Trade Agreement (Nafta) between the two countries and Mexico.
Mr Trump held a breakfast meeting at the White House with a dozen business leaders including Elon Musk, the Tesla and SpaceX founder, and executives from Dell, Johnson & Johnson, US Steel and Lockheed Martin.
He warned them he would impose a "substantial border tax" on companies moving their manufacturing out of the US, and promised tax breaks for those producing in America.
"All you have to do is stay," he said. "A company that wants to fire all of its people in the United States, and build some factory some place else, and then thinks that that product is going to just flow across the border into the United States - that's not going to happen."
He also tasked the business leaders to come up with a plan to help stimulate the manufacturing sector and present it within 30 days.
On a packed first day, Mr Trump also met with construction union leaders, and Republican members of Congress to discuss repealing the Affordable Care Act, Mr Obama's signature healthcare policy.
John McCain, the influential Republican senator, criticised Mr Trump's withdrawal from TPP. He said: "It's a serious mistake that will have lasting consequences for America's economy and our strategic position in the Asia-Pacific region."
However, Senator Bernie Sanders, the former Democratic presidential hopeful, who like Mr Trump was critical of TPP, said: "I am glad the Trans-Pacific Partnership is dead and gone. For the last 30 years, we have had a series of trade deals, including Nafta, which have cost us millions of decent-paying jobs."
A legal case filed in New York by the group Citizens for Responsibility and Ethics in Washington contended that Mr Trump was "submerged in conflicts of interest" because of ties with countries such as China, India and potentially Russia. It cited a constitutional provision known as the "emoluments" clause that bars US officials from accepting gifts from foreign governments.
The group claimed that should include payments by foreign governments for leases at Trump Tower in New York, visits to Mr Trump's hotels, rounds at Trump's golf courses, and rights to rebroadcast Mr Trump's reality TV show 'The Apprentice'.
Meanwhile, Mr Spicer, the combative White House spokesman, stood by his controversial claims that Mr Trump's inauguration was watched by more people than that of Mr Obama eight years ago. Mr Spicer accused the media at the weekend of "deliberately" underestimating the size of the crowd.
Speaking during his first daily White House press briefing yesterday, Mr Spicer said he did believe it was his duty to tell the truth. He said: "It is an honour to do this and yes I believe we have to be honest with the American people. Our intention is never to lie to you.
"I think sometimes we can disagree with the facts. I'm going to come out here and tell you the facts as I know them. And if we make a mistake, we'll do our best to correct it."