President Trump on Saturday said “UNFAIR” trade practices can “no longer be tolerated,” noting the U.S. “must be treated fairly.”

The president suggested that the country’s trade practices prior to his administration was “not Free or Fair Trade,” but “Stupid Trade.”

“The United States must, at long last, be treated fairly on Trade. If we charge a country ZERO to sell their goods, and they charge us 25, 50 or even 100 percent to sell ours, it is UNFAIR and can no longer be tolerated. That is not Free or Fair Trade, it is Stupid Trade!” Trump tweeted Saturday afternoon.

The president’s tweets come after the administration’s decision this week to slap tariffs on allies Canada, Mexico and the European Union’s steel and aluminum shipments to the U.S., resulting in an impending trade war. The White House also threated China with separate tariffs.

Europe, Mexico, Canada and China have vowed to hit back at U.S. goods.

Mexico plans to retaliate against the tariffs by targeting U.S. cheese, among other products, while Europe is threatening to target Kentucky bourbon and Wisconsin-based motorcycles Harley-Davidson. The jeans maker Levi Strauss is also on the EU’s target list.

The president initially introduced tariffs on steel and aluminum in March but carved out an exception for Canada and Mexico during North American Free Trade Agreement (NAFTA) negotiations.

The president instituted tariffs of 25 percent on steel and 10 percent on aluminum imports earlier this year.

"We will not place any new tax on products made in the United States," Trump said in March. "You don't want to pay a tax, bring your plants to the United States."

He added: "We're urging all companies to buy American. That's what we want. Buy American."

The Associated Press contributed to this report.