ISTANBUL

South Korean Prime Minister Kim Min-seok said Monday that Washington and Seoul are making progress on tariff-related issues, following a talk with US Vice President JD Vance on the phone last month, local media reported.

Kim's remark came amid controversy over the government's lack of preparedness for US President Donald Trump's recent threat to raise tariffs on South Korea from 15% to 25%, Seoul-based Yonhap News reported.

"It's not just the hotline that's in operation, but various existing channels of contact, including the hotline with Vice President Vance, were all put into operation, and through a process of learning each other's true intentions, it is progressing into what we see now," Kim told reporters at his official residence.

Trump's surprise announcement on social media prompted top South Korean trade officials to rush to Washington to meet with their counterparts and resolve uncertainties surrounding the tariff issue.

"This issue was about President Trump's unique messaging method," he said.

Kim also rebuffed reports that Trump's threat was related to South Korea's investigation into a data breach at the US-listed e-commerce giant Coupang.

"That interpretation is completely different from the truth," he said.

Separately, South Korean stocks nosedived on Monday by more than 5%.

The Korean won plunged against the US dollar as the benchmark Korea Composite Stock Price Index tumbled 274.69 points to close at 4,949.67.