President Donald Trump has accused Argentina and Brazil of hurting US farmers through currency manipulation and has said he will slap tariffs on their steel and aluminium imports.
Mr Trump also is calling on America’s central bank to act to prevent other countries from devaluing their currencies.
Both South American nations were among US allies that Mr Trump had exempted from steel and aluminium tariffs in March 2018.
Hours before he was to depart for a Nato conference in London, Mr Trump tweeted that “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 & aluminium that is shipped into the US from those countries.”
Mr Trump said the Federal Reserve should “lower rates & loosen”.