Trump twinned his threat to Brazil with the promise of a 50% tariff on copper, which would strike at the economic lifeline of two more Southern neighbors, Chile and Peru. The president capped his week by setting a 30% tariff on Mexican imports as of Aug. 1.

Brazil’s chief prosecutor has called for a guilty verdict in the case of far-right former President Jair Bolsonaro, who is on trial accused of leading an alleged coup plot.

Jamieson Greer, the U.S. trade representative, said Tuesday that he was beginning the investigation “into Brazil’s attacks on American social media companies as well as other unfair trading practices...