US President Donald Trump has said he will restore tariffs on steel and aluminium imports from Brazil and Argentina.
He suggested the countries’ weak currencies and cheap exports were harming US farmers.
“Brazil and Argentina have been presiding over a massive devaluation of their currencies,” Mr Trump said.
Brazil’s President Jair Bolsonaro said he would seek talks with Mr Trump.
Argentine production minister Dante Sica said he too would request a conversation with his US counterparts.
For Mr Trump, farmers in rural states are an important block of voters, and they have had a difficult time in the past year.
Across the country, farm bankruptcies have surged 24% since September 2018, a few months after US trade disputes with China and other countries led to higher tariffs on key farm goods including soyabeans, cotton and dairy, according to analysis by the American Farm Bureau Federation.