Seoul: South Korean stocks opened sharply lower Monday as concerns have risen about a broader conflict in the Middle East after Iran-backed Houthi militants in Yemen joined the war. After opening 4.73 percent lower, the benchmark Korea Composite Stock Price Index (KOSPI) fell 240.94 points, or 4.43 percent, to 5,197.93 in the first 15 minutes of trading. According to Yonhap News Agency, risk-off sentiment has deepened as the conflict, which began in late February following U.S.-Israeli strikes on Iran, has shown signs of further escalation. The Houthis fired missiles at Israel over the weekend, warning they would continue operations until attacks on Iran cease. It marked their first military action since the start of the war in the Middle East a month ago. Following the move, global oil prices climbed as fears of further disruptions to oil supplies intensified. U.S. President Donald Trump said negotiations with Iran to end the war are under way, but Washington has ordered thousands of troops to move to the region, stoking fears of ground operations. Most big-cap shares lost ground. Market bellwether Samsung Electronics slid 3.9 percent, while chip giant SK hynix sank 5.42 percent. Top automaker Hyundai Motor dropped 5.66 percent, while its sister affiliate Kia tumbled 5.52 percent. Leading battery maker LG Energy Solution lost 1.2 percent, and artificial intelligence investment firm SK Square dipped 6.07 percent. Bio giant Samsung Biologics decreased 4.3 percent, and Celltrion went down 3.25 percent. Defense giant Hanwha Aerospace declined 4.87 percent, and nuclear power plant builder Doosan Enerbility fell 5.76 percent. Leading shipbuilder HD Hyundai Heavy and its rival Hanwha Ocean lost 6.72 percent and 5.6 percent, respectively. The local currency was trading at 1,513.85 won against the greenback at 9:15 a.m., down 4.95 won from the previous session.