WASHINGTON, Dec. 2 (Xinhua) -- U.S. President Donald Trump announced Monday that the United States will restore the tariffs on steel and aluminum imported from Brazil and Argentina "effective immediately."

"Brazil and Argentina have been presiding over a massive devaluation of their currencies, which is not good for our farmers," Trump said in a tweet on Monday morning.

"Therefore, effective immediately, I will restore the Tariffs on all Steel & Aluminum that is shipped into the U.S. from those countries," he said.

The U.S. president then again lashed out at the Federal Reserve, pressing it to lower interest rates and loosen monetary policy so that many countries can "no longer take advantage of" a strong dollar.

Brazilian President Jair Bolsonaro told reporters Monday that he would discuss the issue with Economy Minister Paulo Guedes and talk to the U.S. president directly if necessary. "I have an open channel with Trump," he said.

Amid strong opposition, the Trump administration slapped tariffs on imported steel and aluminum globally last year citing national security concerns. In May, Trump removed the tariffs on Canada and Mexico, in hope that the U.S. Congress would ratify the U.S.-Mexico-Canada Agreement, a new trade agreement reached late last year.

Brazil and Argentina reached deals with the U.S. administration to receive exemptions to the steel and aluminum tariffs. Trump's surprise announcement came a few months after Brazil and the United States officially began negotiating a trade agreement in July.

The U.S. president's accusation of "massive" currency devaluation contradicted the conclusion of the Treasury Department, which said in its semi-annual report in May that no major trading partner of the United States meets the standard of currency manipulation.