U.S. President Donald Trump has issued a sweeping new threat to impose tariffs on any country supporting what he called the “anti-American” policies of the BRICS economic bloc, as his administration prepares to dispatch formal tariff notices to dozens of nations starting Monday.

In a statement posted on Truth Social on Sunday, Trump announced that the United States would levy an additional 10% tariff, with no exceptions, on countries aligning themselves with the expanding BRICS coalition. The president did not specify which policies of the group he considered anti-American.

BRICS, comprising Brazil, Russia, India, China, and South Africa, has grown in recent years to include Egypt, Ethiopia, Indonesia, Iran, and the United Arab Emirates, with a further ten countries, including Nigeria, Thailand, and Belarus designated as partners. The group advocates for a multipolar world order and has openly opposed unilateral trade restrictions, a stance seen as a veiled critique of U.S. trade policy.

Trump’s new warning follows the expiration of a 90-day pause on U.S. tariffs, which ends Wednesday. In his posts, the former president said formal letters would begin going out to dozens of countries on July 7, detailing new trade terms or imposing baseline tariffs. He added that more letters would be issued on Tuesday and Wednesday, with the goal of reaching agreements or issuing notices to most nations by July 9.

“We’re going to be sending letters out on Monday having to do with the trade deals. Could be 12, maybe 15… and we’ve made deals also,” Trump told reporters on Sunday in New Jersey. He noted that without progress, countries would revert to pre-April tariff levels starting August 1.

Trump’s administration says it has already reached deals with three nations: the United Kingdom, China, and Vietnam. China agreed to reduce its steep import duties temporarily, while the UK maintained a 10% tariff and Vietnam accepted a 20% minimum rate on its exports to the U.S.

Meanwhile, countries that have yet to engage in negotiations will receive one of about 100 letters, according to Bessent. Many of these are directed at smaller nations with minimal trade volumes, which he said would be assigned the baseline 10% duty.

Commerce Secretary Howard Lutnick added that formal tariff enforcement will begin August 1 and confirmed that negotiations remain ongoing with several countries. However, he declined to provide specifics.

The announcement comes as Brazil hosts the latest BRICS summit, where leaders issued a joint statement criticizing the rise of unilateral tariffs, a move seen as a direct rebuke of Trump’s trade agenda. The summit also discussed cross-border payment systems and condemned recent military actions in member state Iran.

China responded to Trump’s remarks on Monday, stating it opposes the use of tariffs as tools for coercion and asserting that BRICS is not aimed at confronting any specific country.

Economists have raised concerns that Trump’s expanding trade war could drive up consumer costs and global instability. Critics, including former Treasury Secretary Larry Summers, warn the tariffs could spark inflation and weaken American competitiveness. However, White House officials maintain that tariff revenue is increasing and that there’s no lasting evidence of economic harm.