European leaders said they would respond firmly to higher levies on steel and aluminum, but they had yet to say what that retaliation would look like.

President Donald Trump signed an order Monday imposing global tariffs of 25% on all steel and aluminum imports in a move that will likely please domestic steelmakers but hurt allies like Canada and Mexico.

Mexico, Canada and the European Union on Tuesday condemned U.S. President Donald Trump's decision to impose tariffs on all steel and aluminum imports next month, a move that has fanned fears of a trade war as business and political leaders braced for yet more trade duty announcements from the new administration.

The European Union vowed a response to 25% tariffs President Donald Trump said the US will impose on steel and aluminum imports, escalating a potential trade dispute between transatlantic allies.

The president imposed a 25 percent tariff on global metals, repeating a move from his first term. Economists and foreign governments know what will come next.

French steelmaker Aperam on Tuesday called on Brussels to intervene to curb imports if new 25% tariffs on all steel and aluminium imports into the United States prompt companies to ship more to the European Union instead.

U.S. President Donald Trump signed proclamations late on Monday to raise tariffs on all steel and aluminium imports to 25% without exceptions or exemptions. A White House official confirmed that the measures would take effect on March 4.

The European Union plans to safeguard its economic interests by imposing countermeasures in response to the U.S. tariffs, according to EU officials.

European shares were largely unchanged on Tuesday after a record close in the previous session, with investors assessing the risks of an escalating trade war after U.S. President Donald Trump raised tariffs on metals.

The 25 percent tariffs on imported steel and aluminum are the latest salvo in his ongoing effort to overhaul the U.S. trading relationship with the rest of the world.

Trade Minister Douglas Alexander said the UK would not have "a knee-jerk reaction" but "a clear-headed" response.