Seoul: Stocks opened lower Tuesday after U.S. President Donald Trump unexpectedly announced that Washington will raise tariffs on South Korean automobile and other products to 25 percent from 15 percent. The Korea Composite Stock Price Index (KOSPI) fell 41.39 points, or 0.84 percent, to 4,908.20 in the first 15 minutes of trading.

According to Yonhap News Agency, Trump revealed through a social media post that the United States will increase tariffs on automobiles, lumber, pharmaceutical goods, and "all other" reciprocal tariffs. He criticized the South Korean parliament for not approving what he describes as a "Historic Trade Agreement." This refers to a bill submitted by the ruling Democratic Party to the parliament in November, which aims to implement a bilateral trade and investment deal that remains unpassed.

Last year, the two countries reached a trade agreement under which South Korea committed to investing US$350 billion in the U.S. in return for a reduction in tariff rates.

In response to the tariff announcement, key stocks experienced declines. Samsung Electronics, a top tech giant, moved down 1.45 percent, while No. 2 chipmaker SK hynix saw no change. Leading carmaker Hyundai Motor experienced a drop of 3.55 percent, and its sister company Kia lost 4.9 percent. Aerospace firm Hanwha Aerospace shed 1.58 percent.

The pharmaceutical sector also opened weak, with Samsung Biologics falling 0.5 percent and Celltrion decreasing by 2.79 percent. However, utility service providers saw gains, with KEPCO rising 2.48 percent and Korea Gas increasing by 0.5 percent.

The local currency was trading at 1,449.4 won per U.S. dollar at 9:15 a.m., marking a decline of 8.8 won from the previous session.