That exemption was due to expire on Friday. Eastern Time on Friday.
"The U.S. has sought to use the threat of trade restrictions as leverage to obtain concessions from the EU".
Europe, Canada and Mexico say that as close allies of the USA they should receive exemptions from the measures.
This comes after USA and EU trade officials spent two months trying to reach an agreement to create a tariff exemption for European countries.
As with those moves, the White House decision to apply the duties of 25 per cent on steel and 10 per cent on aluminum against the European Union left the bloc wondering about the value of trans-Atlantic relations and vowing steps to counter the impact.
It's a bad day for world trade.
"That Canada could be considered a national security threat to the United States is inconceivable", MrTrudeau said. European Union exports potentially subject to US duties are worth 6.4 billion euros ($7.5 billion). United States leaves us no choice but to proceed with a WTO dispute settlement case and the imposition of additional duties on a number of U.S. imports.
The tariffs are aimed at allowing the USA steel and aluminum industries to increase their capacity utilization rates above 80 percent for the first time in years. Growing trade tensions have clouded a benign outlook for the global economy, which is on track to grow at its fastest pace since 2011 this year and next, according to the International Monetary Fund.
The Canadian tariffs will be 25 percent on steel and 10 percent on aluminum, and aim to match USA penalties on a dollar-for-dollar basis based on export values, according to Foreign Affairs Minister Chrystia Freeland. However, Ross said NAFTA talks are "taking longer than we had hoped" and said "there is no longer a precise date when they may be concluded". "We are awaiting their reaction". He estimated the USA tariffs would affect $4 billion in trade between the two countries. "Both Canada and Mexico will be put off by these tariffs and may be less likely to agree to anything for fear of looking like they are caving in to Trump's bullying".
French President Emmanuel Macron, meanwhile, called the move was illegal.
The three close USA allies had been part of a small group of foreign governments that received temporary exemptions from the tariffs, until trade deals could be signed.
Freeland pointed out that 50 per cent of American steel exports go to Canada, calling her government's countermeasures "meaningful".
Loomis says there are 10,000 jobs directly related to the production of steel in Hamilton and those support another 30,000 spin off jobs.
President Donald Trump concurred in a March proclamation with Commerce Secretary Wilbur Ross's findings from the January reports that included "steel mill articles are being imported into the United States in such quantities and under such circumstances as to threaten to impair the national security of the United States".
"We have made clear to the US Government at the highest levels the importance of United Kingdom steel and aluminium to its businesses and defence projects".
The action was mainly targeted at China over accusations of flooding the global market with cut-rate metals and dragging down prices. And it won't be on USA steel and aluminum - it will be on Harley Davidson motorcycles, California almonds, Levis and Jack Daniels. Noting her discussions with USA officials, she said. "For the economy overall, it's just a very small fraction of 1 percent", he said in an interview on CNBC.