A carrier cargo ship docked in Ulsan, South Korea, on Jan. 21.SeongJoon Cho / Bloomberg via Getty Images

President Donald Trump said Monday that he was hiking tariffs on imports from South Korea to 25% from 15%, complaining that the nation`s legislature wasn`t "living up" to a trade deal that was struck last year.

"Because the Korean Legislature hasn`t enacted our Historic Trade Agreement, which is their prerogative, I am hereby increasing South Korean TARIFFS on Autos, Lumber, Pharma, and all other Reciprocal TARIFFS, from 15% to 25%," Trump wrote in a social media post.

Trump`s announcement comes as he also contends with blowback from voters on affordability and the cost of living. His tariffs have contributed to stubborn price inflation, and recent research says consumers have shouldered nearly all of costs from the duties.

South Korea is an important trading partner for the United States, ranking among the top 10 sources of imports. Nearly $150 billion worth of goods is imported every year from South Korea to the U.S. by companies and consumers.

In July, Trump reached what he called a trade deal with South Korea`s president. However, the two sides then remained deadlocked for months over an investment pledge that the U.S. pushed for.

Then in October, during Trump`s Asia trip, he and South Korean President Lee Jae Myung finalized that deal, which included a promise of investing $350 billion in the U.S.

Weeks later, in November, the White House and South Korean government released a "fact sheet" that was set to put the deal in motion.

The deal featured lower tariffs for both sides, with imports coming into the U.S. capped at a 15% rate, down from the 25% duty announced earlier in 2025 on "Liberation Day" in April, which sent markets into a tailspin.

Trump`s latest tariff announcement follows at least three other threats that the administration never followed through on, including the threat of 10% on Canada after Ontario ran an anti-tariff World Series ad, tariffs on European countries over Greenland, and 100% on Canada which was threatened on Saturday.

Trump`s renewed tariff threats also come as the Supreme Court continues to consider the legality of his sweeping trade agenda. Administration officials have maintained in court that they are necessary. However, Trump has used them to lash out at world leaders he dislikes.

Last week, Trump said he imposed higher tariffs on Switzerland because the nation`s president "rubbed me the wrong way."

The court could rule on the fate of the global tariffs in the coming weeks.