On Monday, US President Donald Trump fulfilled his commitment to impose 25 per cent tariffs on steel and aluminium imports, further intensifying a long-promised trade war while getting warnings from Europe and China.

While travelling to the Super Bowl in Louisiana on Air Force One, the Republican president announced the policy on Sunday. Prior to Trump signing the executive orders to enforce the measures, global stock markets saw an increase as traders, experiencing "tariff fatigue," seemed to dismiss Trump's plans.

In the Oval Office, "Today I'm simplifying our tariffs on steel and aluminium," Trump said. "It's 25 per cent without exceptions or exemptions." Trump also hinted at imposing additional tariffs on automobiles, pharmaceuticals and computer chips. As per the US trade data, Trump has already threatened Canada and Mexico with tariffs, which are the largest steel importers to the United States, and right now, Brazil and South Korea have become the foremost steel providers. 

National Economic Council Director Kevin Hassett informed CNBC, "President Trump has made it clear that an important part of an America First Golden Age is steel production ". The U.S. president stated that he was evaluating the possibility of exempting Australia from the steel tariffs, echoing remarks previously made by Australian Prime Minister Anthony Albanese. "We have a (trade) surplus to Australia, one of the few. And the reason is they buy a lot of airplanes. They are rather far away and need lots of airplanes," he conveyed.

Trump has also vowed to make an announcement on Tuesday or Wednesday regarding broader "reciprocal tariffs" aimed at matching the duties imposed by other governments on U.S. products. During his 2017-2021 presidency, he implemented extensive tariffs to shield U.S. industries, arguing that they were unfairly challenged by competition from Asian and European nations.

Canadian steel producers cautioned that the tariffs could cause "massive" disruptions. At the same time, the European Commission asserted that it would "react to protect the interests of European businesses, workers and consumers from unjustified measures."

In an interview broadcast on Sunday, French President Emmanuel Macron pledged to take a confrontational stance on Trump's threat of more enormous tariffs against the European Union. However, he said the United States should concentrate its measures on China.

German Economy Minister Robert Habeck stated that a tariff dispute would result in "only has losers." According to consultancy Roland Berger, approximately 25 per cent of Europe's steel exports are directed to the United States. Britain’s steel industry organisation described the proposed tariffs as a "devastating blow."

Trump has previously demonstrated a willingness to use the United States' economic power as a tool, imposing tariffs on major trade partners such as China, Mexico, and Canada shortly after taking office. Although he initially delayed the 25% tariffs on Canada and Mexico for a month following their commitments to strengthen efforts against fentanyl trafficking and illegal immigration, he proceeded with tariffs on China. As a result, Chinese goods entering the U.S. were subjected to an additional 10% tax. In response, China has imposed retaliatory tariffs on U.S. coal and liquefied natural gas, which are set to take effect on Monday.

On Monday, Chinese foreign ministry spokesperson Guo Jiakun said, "there is no winner in a trade war and tariff war."

During Japanese Prime Minister Shigeru Ishiba's visit last week, Trump highlighted the steel industry.

The U.S. president said he had secured a deal for Japan’s Nippon Steel to invest significantly in US Steel rather than attempting to take over the struggling company.

Trump, who has pledged a "new golden age" for the country, maintains that any tariffs imposed would primarily affect foreign exporters and not lead to higher costs for American consumers, despite most experts disagreeing with this claim.

However, he did admit earlier this month that Americans might initially experience some economic "pain" due to the tariffs.

Despite concerns over the tariffs, Wall Street’s major indices closed higher on Monday, with London and Frankfurt reaching new records. Stocks in Hong Kong and Shanghai also saw gains.

The research director at trading group XTB, Kathleen Brooks, said, "The fact that global equity indices are higher at the start of the week could be a sign of tariff fatigue ".

On Monday, the dollar strengthened against the Canadian Dollar and Mexican peso, and the South Korean won.