U.S. President Donald Trump warned that countries seeking to take advantage of the U.S. Supreme Court ruling that ‘reciprocal tariffs’ are unlawful would face higher retaliatory tariffs. U.S. experts advised that, because Section 301 of the Trade Act and other measures Trump has floated as alternatives to reciprocal tariffs offer ‘considerable room to maneuver,’ they should “for now, implement existing trade agreements and watch the next steps.”

On the 23rd (local time), President Trump wrote on social media, “If any country tries to play games with the Supreme Court’s ridiculous decision, especially those that have plundered the United States for years, even decades, they will face tariffs higher than what they recently agreed to, and worse.” He added the commercial caveat, “Buyer beware!!!”

This is interpreted as a warning that if countries that pledged large-scale investment in the United States or purchases of U.S. goods in exchange for lower reciprocal tariffs renege on those commitments citing the Supreme Court ruling, he will impose steep retaliatory tariffs.

In another post, Trump said, “As president, I do not have to go back to Congress to get approval for tariffs; that approval was granted long ago, in many forms.” This underscored his claim that he can push through tariffs under his own authority based on Sections 122 and 301 of the Trade Act and Section 232 of the Trade Expansion Act.

Kate Kalutkiewicz, who served as a White House trade adviser during Trump’s first term, said at a seminar hosted by the U.S. think tank Korea Economic Institute (KEI) that the president’s remarks were “clearly a message aimed at the European Union (EU) and India, and an important signal that he intends to keep an eye on trade partners, including South Korea.” She said, “Because President Trump’s next cards have not all been revealed, it seems wise for trade partners to catch their breath for now and watch the next moves.”

Peter Harrell, who served as senior director for international economics at the White House under the Joe Biden administration, also said, “If asked for my advice, I would also counsel continuing to implement trade agreements,” adding, “In light of the Court’s ruling, it has become harder to impose the 40-50% tariff rates of the past, but President Trump still retains the legal authority to threaten 10-20% tariffs.” He went on to say that over the coming months, “tariffs on semiconductors and pharmaceuticals under Section 232 will be critical,” and that “President Trump has various tools of pressure, such as imposing high tariffs on those items against countries that backtrack on trade deals, or raising auto tariffs from 15% to 20-25%.”

Kalutkiewicz in particular said that Section 301, which the Office of the U.S. Trade Representative (USTR) has announced it has begun investigating, would give President Trump “considerable room to maneuver.” Because Section 301 requires procedures such as investigation, consultations, and public comment, it takes time to invoke, but once a basis is established, there is broad discretion to adjust tariffs thereafter. She noted that “the yearlong investigation of China under Section 301 during Trump’s first term is still being used as the basis for changes to tariffs on China,” adding that “the Biden administration also used that basis to raise tariffs on Chinese electric vehicles to as high as 100%.”

On the refunds of reciprocal tariffs that the Supreme Court invalidated, Kalutkiewicz advised that “regardless of nationality, any importer of record is eligible for a refund,” but cautioned that “if pursuing refund litigation, it is important to be careful about public messaging.” She said this is because “President Trump may publicly criticize companies seeking refunds, and public opinion may form that companies are trying to pocket tariffs that were passed on to consumers.” She added that “it may be better to announce investments in things like improving employee treatment.”