US officials said on Wednesday that they will sanction Brazilian Supreme Court judge Alexandre de Moraes, accusing him of authorising "arbitrary pre-trial detentions" and suppressing "freedom of expression".
Judge Moraes has been leading the investigation into allegations that Brazil's former right-wing President Jair Bolsonaro and his allies plotted a coup after he lost the 2022 election.
Bolsonaro has denied those allegations and has called Judge Moraes a "dictator".
Shortly after the sanctions were announced, US President Donald Trump signed an executive order that raised tariffs on Brazil to 50%.
Trump had threatened to impose the steep tariffs earlier this month in a letter he shared on social media to Brazil's current president Luiz Inácio Lula da Silva.
