WASHINGTON, United States (AFP) — President Donald Trump threatened nations Monday with punishing hikes on import duties if they choose to “play games” after the United States (US) Supreme Court struck down his global tariffs last week.

“Any country that wants to ‘play games’ with the ridiculous Supreme Court decision, especially those that have ‘ripped off’ the USA for years, and even decades, will be met with a much higher tariff, and worse, than that which they just recently agreed to,” Trump wrote on social media.

The high court’s decision has dealt a sharp blow to Trump’s economic agenda, of which tariffs — and his ability to impose them rapidly — have been a key feature.

For now, US Trade Representative Jamieson Greer has said that he expects partners to “stand by” the tariff deals they have struck with Washington.

After the Supreme Court ruled against Trump’s country-specific tariffs last week, saying he exceeded his authority in tapping emergency economic powers to impose them, the US leader turned to a separate law to announce new 15 per cent duties on imports.

Trump insisted in a separate Truth Social post Monday that “as president, I do not have to go back to Congress to get approval of tariffs”.

He also claimed that the court gave him “far more powers and strength” with its ruling, and that he could use “licenses to do absolutely ‘terrible’ things to foreign countries”.