Brazilian President Luiz Inacio Lula da Silva on Thursday said that he would not take orders from a “gringo,” responding to U.S. President Donald Trump’s letter slapping Brazil with 50% tariffs.

In a letter last week, Trump attributed the tariffs, set to start in August, to Brazil’s treatment of former President Jair Bolsonaro and to alleged unfair trade practices by Brazil against U.S. companies.

Lula and members of his cabinet have rejected the reasoning behind the tariffs and insisted on Brazil’s sovereignty, while calling for trade negotiations with the United States.

“No gringo is going to give orders to this president,” Lula said, wearing a bright red shirt as he addressed a gathering of leftist student activists in the state of Goias. In Brazil, ‘gringo’ is a common term for foreigners, without the pejorative sense it carries in other parts of Latin America.

He added that Brazil would go forward with regulation and taxation of U.S. tech firms, alleging that they promote violence and fake news under the argument of freedom of expression.

Foreign Relations Minister Mauro Vieira told CNN Brasil separately on Thursday that Lula was open to talks with Trump, though they had not yet met.

“If the circumstances are given, they will speak,” he added.

Brasilia has been holding discussions with industry groups and companies affected by the U.S. tariff, while also readying potential retaliatory measures if talks fall through.

Lula, who is in his third non-consecutive term as president of Latin America’s largest economy, saw his approval ratings start to rebound after the trade spat with Trump last week.

The Brazilian leader was expected to make a televised address to the nation later on Thursday.