Donald Trump's insistence that "spoiled" Japan imports more US rice is adding to Prime Minister Shigeru Ishiba's problems ahead of elections that could sink his premiership after less than a year in office.

It shows that personal grudges rather than simple economics are a driving force in the U.S. leader’s use of tariffs.

"America will, once again, build a DOMINANT Copper Industry," Trump said in a post on his Truth Social media platform.

President Donald Trump's threats to impose high tariffs on countries make U.S. trading partners and investors nervous. But his sector tariffs could hurt consumers and businesses more in the long run.

STORY: The European Union said it was working on sealing a trade deal with the U.S. by the end of the month.European Commission President Ursula Von der Leyen said the EU was working closely with the Trump administration to reach a deal.

U.S. President Donald Trump's latest tariff delay provided some hope to major trade partners Japan, South Korea and the European Union that deals to ease duties could still be reached, while bewildering some smaller exporters such as South Africa and leaving companies with no clarity on the path forward.

In his new round of tariffs being announced this week, Trump is essentially tethering the entire world economy to his instinctual belief that import taxes will deliver factory jobs and stronger growth in the U.S., rather than the inflation and slowdown predicted by many economists.

Trump shared screenshots of letters detailing new tariff rates for over a dozen countries, allowing room for further negotiations before the renewed deadline of Aug. 1.