U.S. President Donald Trump on Monday signed executive orders imposing a 25 percent tariff on steel and aluminum imports, effective March 12. The move marks a significant escalation in trade tensions despite warnings from the European Union, China, and other major trading partners.

Speaking from the Oval Office, Trump said, "Today, I’m simplifying our tariffs on steel and aluminum. It's 25 percent without exceptions or exemptions."

The executive order specifies that aluminum imports from Argentina, Australia, Canada, Mexico, the EU, and the UK will face the additional tariff. A separate order targets steel imports from the same countries as well as Brazil, Japan, and South Korea.

Trump hinted at further measures, including tariffs on automobiles, pharmaceuticals, and computer chips. National Economic Council Director Kevin Hassett emphasized the administration's goal to revitalize domestic steel production, calling it essential to Trump's vision of an "America First Golden Age."

Trump also promised an upcoming announcement on broader "reciprocal tariffs" to match the duties imposed on U.S. goods by other nations.

The European Commission vowed to defend European businesses from what it described as "unjustified measures." French President Emmanuel Macron pledged to challenge Trump's tariff strategy, while Germany's economy minister Robert Habeck warned that a tariff conflict would leave "only losers."

Canada, one of the largest exporters of steel to the U.S., expressed concern over potential "massive disruption." The British steel industry labeled the move a “devastating blow.”

China, already locked in trade disputes with the U.S., retaliated by imposing tariffs on American coal and liquefied natural gas. Chinese foreign ministry spokesman Guo Jiakun remarked, “There is no winner in a trade war and tariff war.”

Despite the looming trade war, Wall Street's main indices closed higher on Monday. European markets also hit record highs, although Asian markets remained mixed.

Kathleen Brooks, research director at XTB, suggested that the market's resilience might reflect "tariff fatigue" among investors.

As Trump's tariffs loom, global trade relationships face a period of heightened uncertainty, with significant implications for both consumers and exporters.