The benchmark Korea Composite Stock Price Index rose 13.14 points, or 0.55 percent, to 2,386.28 as of 11:20 a.m.
The main index rose for a second consecutive session after a week-long losing streak due to foreign selling.
Foreigners continued to sell local stocks for a fifth straight session, offloading about 830 billion won ($725 million) stocks in the past four sessions amid rising tensions between North Korea and the United States over the former's nuclear and missile development programs.
US President Donald Trump said Tuesday he is "totally prepared" to use military options against North Korea. His latest warning came in response to Pyongyang's threat a day earlier to shoot down approaching American bombers, even if they are in international airspace.
Large-cap stocks were mixed across the board.
Market bellwether Samsung Electronics Co. fell 0.55 percent, No. 2 chipmaker SK hynix Inc. shed 0.24 percent and leading mobile carrier SK Telecom Co. was up 0.78 percent.
Among gainers, top carmaker Hyundai Motor Co. rose 2.38 percent, leading steelmaker POSCO climbed 0.48 percent and dominant cosmetics maker AmorePacific Corp. was up 2.58 percent.
The local currency was trading at 1,145.75 won against the US dollar, up 3.35 won from the previous session's close. (Yonhap)