The reimposition of Trump's higher tariffs, and also retaliatory measures from U.S. trading partners who did not reach a deal in time, threatens to pull global trade back to where it was in April, with widespread disruption, market volatility, and looming economic pain.

The group of emerging economies—including Brazil, Russia, India and China—has long sought to present itself as a multilateral counterweight to a U.S.-dominated world order.

Trump said the U.S. will impose an additional 10% tariff on any countries aligning themselves with the "Anti-American policies" of the BRICS group of developing nations, whose leaders kicked off a summit in Brazil.