(LEAD) Seoul stocks open markedly lower amid escalating Middle East conflict

## Summary
(ATTN: ADDS more details throughout) SEOUL, March 31 (Yonhap) -- South Korean stocks opened markedly lower Tuesday as U.S. President Donald Trump renewed threats against Iran, with no end in sight to the monthlong war in the Middle East. On Monday (U.S. time), Trump threatened to "completely obliterate" Iran's Kharg Island, a key oil hub, as well as its power plants and oil wells, if a peace deal with the United States is not reached "shortly." The conflict, which began in late February following the U.S.-Israeli strikes on Iran, has been escalating, as Iran-backed Houthi militants in Yemen joined the war, stoking fears of further disruptions to global oil supplies. President Donald Trump speaks during the National Republican Congressional Committee's annual fundraising dinner at Union Station in Washington, D.C., on March 25, 2026, in this image released by AFP. (Yonhap) In Seoul, most big-cap shares lost ground amid heavy selling by foreign investors.

## Article Content
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SEOUL, March 31 (Yonhap) -- South Korean stocks opened markedly lower Tuesday as U.S. President Donald Trump renewed threats against Iran, with no end in sight to the monthlong war in the Middle East.

After opening 2.53 percent lower, the benchmark Korea Composite Stock Price Index (KOSPI) extended losses, falling 203.78 points, or 3.86 percent, to 5,073.52 in the first 15 minutes of trading.

On Monday (U.S. time), Trump threatened to "completely obliterate" Iran's Kharg Island, a key oil hub, as well as its power plants and oil wells, if a peace deal with the United States is not reached "shortly."

The conflict, which began in late February following the U.S.-Israeli strikes on Iran, has been escalating, as Iran-backed Houthi militants in Yemen joined the war, stoking fears of further disruptions to global oil supplies.

Tehran, however, dismissed the peace proposals as "unrealistic, illogical and excessive," while a parliamentary security committee approved a draft bill to introduce a toll system for the Strait of Hormuz, according to foreign media reports.

Israeli Prime Minister Benjamin Netanyahu said the war had achieved more than half its aims, though he did not put a timeline on when it would end.

Overnight, U.S. shares finished mixed. The Dow Jones Industrial Average climbed 0.11 percent, while the tech-heavy Nasdaq Composite sank 0.73 percent. The S&P 500 lost 0.39 percent.



U.S. President Donald Trump speaks during the National Republican Congressional Committee's annual fundraising dinner at Union Station in Washington, D.C., on March 25, 2026, in this image released by AFP. (Yonhap)

In Seoul, most big-cap shares lost ground amid heavy selling by foreign investors.

Market bellwether Samsung Electronics slid 4.76 percent, while chip giant SK hynix sank 7.22 percent.

Top automaker Hyundai Motor dropped 4.05 percent, while its sister affiliate Kia tumbled 4.75 percent.

Leading battery maker LG Energy Solution lost 3.17 percent, and artificial intelligence investment firm SK Square dipped 8.14 percent.

Bio giant Samsung Biologics decreased 0.65 percent, and Celltrion went down 1.64 percent.

Defense giant Hanwha Aerospace declined 4.36 percent, and nuclear power plant builder Doosan Enerbility fell 1.65 percent.

Leading shipbuilder HD Hyundai Heavy shed 0.52 percent, while its rival Hanwha Ocean rose 2.96 percent.

The local currency was trading at 1,523.7 won against the greenback at 9:15 a.m., down 8 won from the previous session.

graceoh@yna.co.kr

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This article covers percent, iran, trump topics. Readability: Flesch-Kincaid grade 0.0. Word count: 391.