US President Donald Trump began his first full day in office yesterday, riding a wave of executive orders signed just hours after his inauguration on everything from immigration to the environment and culture wars.

He used his first hours back in the White House to begin upending the global order, withdrawing the US from international climate and tax agreements, threatening China with tariffs over social media platform TikTok and threatening punitive duties on neighbours Canada and Mexico.

He also signed an executive order declaring a 90-day pause in the disbursement of US foreign development assistance, effectively leaving millions of dollars in aid in limbo.

The aid suspension has the potential to worsen the humanitarian situation for people dependent on aid like the Palestinians in Gaza and the Rohingya refugees in Bangladesh. The decision is now depends on Marco Rubio, who was confirmed as secretary of state by the Senate as the first cabinet member of the new Trump administration.

Signed in front of roaring supporters at an arena and then later in the Oval Office, the long list of policy changes offered a vivid symbol of Trump's increased preparedness versus eight years prior, when he entered the White House with zero governing experience.

The Republican said in a speech after taking the oath at the Capitol -- in a ceremony held indoors due to freezing weather -- that "America's decline is over" after four years of Democrat Joe Biden's presidency, pledging "the golden age of America begins right now."

But after the pomp and ceremony, it was the showman Trump of his first term -- along with the sometimes strongman-style rhetoric -- who was on display later in the day.

Back in the Oval Office, he held an impromptu 50-minute press conference as he signed more orders -- including one pardoning around 1,500 Capitol rioters.

They were charged for taking part in the assault on Congress on January 6, 2021 by thousands of Trump supporters seeking to stop certification of Biden's election victory.

"We hope they come out tonight frankly," Trump said. "They're expecting it."

He also announced plans to weed out some 1,000 opponents from the US government.

He signed orders declaring a national emergency at the Mexican border and said he would deploy US troops to tackle illegal immigration -- a key campaign issue that drove his election victory over Kamala Harris.

The returning president often struck a nationalistic tone, pledging to impose trade tariffs, rename the Gulf of Mexico to the "Gulf of America," and take "back" the Panama Canal, which has been controlled by the Central American country since 1999.

But he played down his earlier promises to get a peace agreement in Ukraine before taking office.

He confirmed he would meet Vladimir Putin and said Putin was "destroying Russia" by not making a deal to end the war.

MONDAY'S EXECUTIVE ORDERS

However, the legal backlash to Trump's second term has begun, with rights groups and state governments firing an early salvo against the Republican's day-one decision to overhaul birthright citizenship.

Late on Monday, organisations including the American Civil Liberties Union (ACLU) and the Legal Defense Fund filed a lawsuit calling Trump's actions unconstitutional, in a case that is likely to test the limits of his executive power.

Yesterday, 18 states also filed a similar lawsuit seeking to ground the order.

Trump signed a record 26 executive orders on Monday. According to White House officials, those 26 executive orders were among the 42 presidential actions Trump took on his first day, including memoranda and proclamations.

Among the executive orders Trump signed with a flourish in front of a cheering crowd was the "ending weaponisation" of government against political opponents.

The US president also signed orders targeting automatic citizenship for US-born children of immigrants in the country illegally.

He rescinded executive orders that had promoted diversity, equity and inclusion (DEI) and promoted rights for LGBTQ+ people and racial minorities, fulfilling promises to curtail protections for the most marginalized Americans.

The Republican leader also declared a "national energy emergency" to expand drilling in the world's top oil and gas producer, said he would scrap vehicle emissions standards that amount to an "electric vehicle mandate," and vowed to halt offshore wind farms, a frequent target of his scorn.

Another order withdrew the United States from the World Health Organization, saying the global health agency had mishandled the Covid-19 pandemic and other international health crises.

Trump also reversed Biden administration sanctions on violent Israeli settlers in a concession to Israeli Prime Minister Benjamin Netanyahu amid a crucial ceasefire deal between Israel and Hamas.

Trump also signed an executive order that he said was aimed at "restoring freedom of speech and ending federal censorship."

He reversed an executive order issued by Biden that moved to lift the US designation of Cuba as a state sponsor of terrorism.

On trade, the US president punted on a campaign pledge to issue tariffs on Canada and Mexico on day one of his new administration. However, he said he would issue the new tariffs on the North American neighbours on 1 February in what would mark an extraordinary about-face in US trade policy that would considerably raise prices for American consumers.

"We are thinking in terms of 25% on Mexico and Canada because they're allowing vast numbers of people … to come in, and fentanyl to come in," Trump said. "I think we'll do it Feb 1."

Mexico was the US's largest trading partner in 2023 with a total two-way goods trade of $807bn, an amount that surpassed US trade with China, according to the US State Department.

He was confident that he could convince Saudi Arabia to normalise relations with Israel under the Abraham Accords, a signature policy of his previous administration.

But when asked whether he could maintain the ceasefire between Israel and Hamas, he said he was "not confident. That's not our war, that's their war."

Meanwhile, EU, German and Chinese leaders took turns defending global cooperation in Davos yesterday as the spectre of new trade wars looms following Trump's return to the White House.

In their speeches, European Commission President Ursula von der Leyen, Chinese Vice Premier Ding Xuexiang and German Chancellor Olaf Scholz offered visions of the world that are mirror opposites to those of the self-professed tariff-loving Trump.

"Protectionism leads nowhere and there are no winners in a trade war," Ding said, without mentioning Trump directly.

Trump is making history -- as both the oldest president ever to take office and as the first felon, after a conviction related to paying a porn star hush money during his first presidential run.

He is also just the second president in US history to return to power after being voted out, after Grover Cleveland in 1893.