Trump was expected to sign more executive orders on Tuesday, after measures issued on Monday that included moves to curb immigration and roll back environmental regulation as well as a 75-day delay in enforcement of a ban on short-video app TikTok.
The Republican president's pardon of 1500 defendants drew outrage from Congressmen and women who were endangered in the January 6, 2021, attack, when thousands of Trump supporters stormed the Capitol in an unsuccessful attempt to prevent Congress certifying his 2020 election loss to Democrat Joe Biden.
President Donald Trump pardoned 1500 prisoners detained over the Capitol riots of January 6, 2021. (AP PHOTO)
The pardons were among orders Trump signed within hours of taking office, returning in a mood of triumph to the White House after winning last November's election. In his inaugural speech he criticised Biden's presidency and portrayed himself as chosen by God to save a faltering nation.
However, he faces a stiff challenge delivering on his promise of a "Golden Age of America" in the face of a closely split Congress, inevitable lawsuits and recalcitrant world leaders.
Trump did not take immediate action to raise tariffs, a key campaign promise, but said he could impose 25 per cent duties on Canada and Mexico on February 1.
Trump's return to the White House has been met with both relief and disappointment across world markets as investors try to work out what the next four years will bring.
The dollar rebounded sharply on Tuesday after plunging hours earlier as Trump's announcements on Monday brought mixed messaging on tariffs and highlighted investors' sensitivity to headlines about trade policy.
Investors worldwide are calculating what the next four years of a Trump presidency will bring. (AP PHOTO)
US stock futures rose after bouncing around on Monday as traders digested Trump's statements on economic policy and trade levies, while European equities eked out small gains.
Trump, 78, is the first president in more than a century to win a second term after losing the White House and the first felon to occupy the White House. The oldest president ever to be sworn in, he is backed by Republican majorities in both chambers of Congress.
Trump has made illegal immigration a signature issue since he first entered politics in 2015 and he began a sweeping crackdown on Monday.
Shortly after the inauguration, US border authorities said they had shut down Biden's CBP One entry program, which had allowed hundreds of thousands of migrants to enter the US legally by scheduling an appointment on an app. Existing appointments were canceled, leaving migrants stunned and unsure of what to do. Opponents of Trump's agenda are likely to challenge it in the courts.
Trump has withdrawn the US from the Paris climate deal for the second time in a decade. (AP PHOTO)
Trump once again withdrew the United States from the Paris climate deal, removing the world's biggest historic emitter from global efforts to fight climate change for the second time in a decade. This second withdrawal will have a bigger impact in the US and globally than the country's first retreat in 2017, analysts and diplomats said.
In other environmental measures, Trump revoked a ban imposed by Biden on new offshore oil and gas development along most of the country's coastlines. The new president is certain to face legal challenges over his authority to do so.
Billionaire Elon Musk is to head the newly-created "Department of Government Efficiency". (AP PHOTO)
He also said the US would leave the World Health Organization, saying the global health agency had mishandled the COVID-19 pandemic and other international health crises. Berlin would try to talk Trump out of this decision, Germany's health minister said on Tuesday.
Other orders revoked Biden administration policies governing artificial intelligence and electric vehicles.
He also imposed a freeze on federal hiring and ordered government workers to return to the office, rather than working from home. He also signed paperwork to create a "Department of Government Efficiency", an outside advisory board headed by billionaire Elon Musk that aims to cut large swaths of government spending.
Trump said he would issue orders to scrap federal diversity programs and require the government to recognise only genders assigned at birth. And he has vowed to change the name of the Gulf of Mexico to the Gulf of America.
