In a ceremony at the White House, Trump signed separate proclamations imposing a 25 percent tariff on imported steel and a 10 percent tariff on aluminum imports.

"It's really an assault on our country,” Trump said in remarks about the amount of steel and aluminum imported into the U.S. before he signed the orders.

The tariffs will take effect in 15 days. The proclamations exempt Canada and Mexico, although Trump said this could be rescinded if the White House does not like the outcome of ongoing renegotiations of the North American Free Trade Agreement (NAFTA). Describing the new rules as “flexible”, Trump said other countries can apply for exemptions.

Currently, about 90 percent of aluminum used in American manufacturing is imported as well as one-third of steel. Industry groups believe consumers will face the brunt of the impact from the tariffs through increased prices for items ranging from beer to cars as well as thousands of other items built of the two metals or packaged inside them.

Trump announced last week that he would implement the tariffs, which led many other Republicans and elements of his own White House to widely criticize the suggestion. Many were concerned the new tariffs could stoke a global trade war.

Gary Cohn, Trump’s top economic advisor, announced his resignation Monday, with White House sources telling media outlets that the decision was based on Trump’s tariff push. Cohn, the former president of Goldman Sachs, was Trump’s director of the National Economic Council and widely seen as a connection between Trump’s administration and Wall Street.

“These so-called ‘flexible tariffs’ are a marriage of two lethal poisons to economic growth – protectionism and uncertainty,” Republican Senator Jeff Flake, who has become known for his denunciation of Trump over the past year, said in a statement immediately after Trump ordered the tariffs.

“Trade wars are not won, they are only lost,” Flake continued. “Congress cannot be complicit as the administration courts economic disaster. I will immediately draft and introduce legislation to nullify these tariffs, and I urge my colleagues to pass it before this exercise in protectionism inflicts any more damage on the economy.”

Anadolu Agency