President Trump said Monday that he will be slapping tariffs on steel and aluminum imported from Brazil and Argentina.

In a pair of early-morning tweets, Mr. Trump said he decided to reinstate the levies because the two South American countries have been "presiding over a massive devaluation of their currencies," which is hurting American farmers.

The tariffs on metal imports from Brazil and Argentina will be restored immediately, he said.

Brazil and Argentina have been presiding over a massive devaluation of their currencies. which is not good for our farmers. Therefore, effective immediately, I will restore the Tariffs on all Steel & Aluminum that is shipped into the U.S. from those countries. The Federal.... — Donald J. Trump (@realDonaldTrump) December 2, 2019

The Trump administration exempted Brazil and Argentina, among other allies, from the 25% steel tariffs and 10% aluminum tariffs it imposed last year. U.S. Trade Representative Robert Lighthizer told Congress in March 2018 that the president decided to "pause" implementation of the metal tariffs because the countries were in the middle of trade talks with the U.S.

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Mr. Trump also urged the Federal Reserve to take action to prevent countries from devaluing their currencies, which he said puts American farmers and manufacturers at a disadvantage.

"The Federal Reserve should likewise act so that countries, of which there are many, no longer take advantage of our strong dollar by further devaluing their currencies. This makes it very hard for our manufactures & farmers to fairly export their goods. Lower Rates & Loosen - Fed!" he tweeted.

.....Reserve should likewise act so that countries, of which there are many, no longer take advantage of our strong dollar by further devaluing their currencies. This makes it very hard for our manufactures & farmers to fairly export their goods. Lower Rates & Loosen - Fed! — Donald J. Trump (@realDonaldTrump) December 2, 2019

The Federal Reserve and its chairman, Jerome Powell, are often a target of Mr. Trump's ire. The president has accused the central bank of holding back economic growth and has at times called for zero or negative interest rates, citing negative rates in some European countries.

The Fed's policymaking committee voted to cut interest rates three consecutive times this year and will meet again December 10 and 11.