WASHINGTON, Jan 20 (Reuters) - Hours after retaking the presidency on Monday, Donald Trump issued pardons to around 1,500 of his supporters involved in the assault on the U.S. Capitol four years ago, demonstrating his authority over the government with decisiveness.

Following an inaugural day steeped in pageantry, Trump initiated a flurry of executive actions aimed at curbing immigration, rolling back environmental measures, and reversing diversity initiatives concerning race and gender. Notably, he refrained from enacting his promised tariffs but indicated the possibility of imposing a 25% import duty on Canadian and Mexican goods from Feb. 1.

The announcement immediately impacted financial markets — the Mexican peso weakened by 1% against the dollar, and the Canadian dollar hit a five-year low at C$1.4515. Stock markets worldwide saw gains erased, while the U.S. dollar surged amid fluctuating trading activity.

Trump’s contentious pardons for those convicted in the Jan. 6, 2021, Capitol attack have incensed law enforcement, legislators, and others who faced mortal danger during one of modern U.S. history’s darkest moments.

During the riot, approximately 140 law enforcement officers were assaulted, facing physical attacks ranging from chemical sprays to blows from pipes and poles. Four lives were lost, including one Trump supporter fatally shot by police. Trump also expedited the early release of 14 prominent members of the far-right Oath Keepers and Proud Boys groups, leaving their criminal records intact.

Earlier in the day, Trump, 78, took the oath of office beneath the Capitol Rotunda — the very site of his supporters’ attempted insurrection in 2021 to overturn his electoral defeat to Joe Biden. Speaking at the ceremony, Trump cast himself as a divinely chosen leader destined to “save America.”

"I was saved by God to make America great again," declared Trump, who has defied legal woes, assassination attempts, and political odds to secure a second term. He is the first president in over a century to return to office after losing it and the first convicted felon to occupy the White House, now backed by Republican control of Congress.

Trump quickly reasserted his long-standing position on immigration. Immediately after his inauguration, U.S. border authorities canceled a program that had previously allowed migrants to enter legally via smartphone appointments. Additionally, he halted flights for nearly 1,660 Afghan refugees, including families of U.S. military personnel, under an order suspending refugee resettlements.

At the White House, Trump signed sweeping executive orders, including one declaring a national emergency at the U.S.-Mexico border, allowing the deployment of military resources there. He also sought to revoke birthright citizenship, a move expected to ignite protracted legal disputes, and designated Mexican drug cartels as terrorist organizations.

Trump doubled down on withdrawing the United States from the Paris climate accord, once again distancing the world’s largest historic polluter from international climate efforts. “We're erasing all the damage caused by the Biden administration,” he remarked while signing numerous executive orders in the Oval Office.

Other directives included reversing Biden-era initiatives on artificial intelligence and electric vehicles, imposing a federal hiring freeze, and ordering the in-person return of remote employees. He also announced the creation of a "Department of Government Efficiency," to be led by billionaire Elon Musk, aimed at drastically reducing federal spending.

In a symbolic shake-up, over a dozen senior nonpartisan diplomats at the State Department were asked to step down in favor of appointees aligned with Trump’s agenda. On his social media platform, Trump revealed plans to terminate over 1,000 Biden administration appointees.

Further executive actions included dismantling federal diversity programs and mandating recognition strictly of genders assigned at birth, policies likely to spark significant controversy.

Despite delivering a speech reflecting a conciliatory and patriotic tone, Trump’s rhetoric was often deeply partisan. He reiterated unfounded claims about foreign countries "dumping prisoners" into the U.S., alongside grievances related to his criminal indictments. Sitting near Biden, Trump took pointed jabs at his predecessor’s policies, accusing the previous administration of prioritizing foreign borders over America’s own.

"This country has spent unlimited resources defending other nations but refuses to protect its own people," Trump asserted.

The inauguration drew tech billionaires Elon Musk, Jeff Bezos, and Mark Zuckerberg, who were seated alongside Trump’s family and cabinet nominees, signaling their alignment with his administration. Musk notably celebrated when Trump vowed to send astronauts to Mars, an ambition Musk has championed for years.

Among other eyebrow-raising proclamations, Trump proposed renaming the Gulf of Mexico to the Gulf of America and expressed intentions to reclaim the Panama Canal, causing ripples among international allies.

Standing alongside Chief Justice John Roberts, Trump was sworn in at 12:01 p.m. ET (1701 GMT), with JD Vance assuming the role of vice president shortly prior. Notably, outgoing Vice President Kamala Harris, defeated by Trump in November, sat with former presidents Barack Obama, George W. Bush, and Bill Clinton during the ceremony. Hillary Clinton, who lost to Trump in 2016, joined her husband Bill, though Michelle Obama opted not to attend. The event was relocated indoors due to severe cold weather nationwide.

Choosing not to attend Biden’s inauguration, Trump has continuously and falsely maintained that the 2020 election was stolen from him.

In one of his final acts in office, Biden issued a raft of controversial pardons, specifically protecting individuals Trump had publicly targeted, such as General Mark Milley, the former Joint Chiefs of Staff chairman. Soon after Trump’s swearing-in, Milley’s portrait was removed from the Pentagon.

Additionally, Biden pardoned five of his family members just minutes before leaving office, citing concerns over potential reprisal from Trump’s administration.