South Korean airline shares declined across the sector as renewed Middle East tensions pushed international oil prices above $100 per barrel. Korean Air fell 2.88% to 28,700 won as of 2:48 p.m. on September 11, while Jin Air dropped 3.41% to 5,940 won and Jeju Air declined 2.45% to 4,785 won. Asiana Airlines slipped 2.03%. October-delivery West Texas Intermediate, or WTI (U.S. oil benchmark), surged 6.69% overnight to settle at $102.48 per barrel, while Brent crude closed at $101.21, its highest level since May 22 and its first settlement above $100 since July 23. Fuel accounts for approximately 30% of airline operating expenses, leaving carriers exposed to sustained oil-price increases. Korean Air's second-quarter operating profit fell 34.4% year over year to 261.8 billion won despite record standalone revenue of 5.0199 trillion won, as fuel costs rose 110.9% to 1.9991 trillion won. Fuel hedging and surcharges can cushion the impact, but airlines cannot fully offset sharp cost increases. September international fuel surcharges rose seven levels to level 21, with Korean Air's one-way surcharge on routes such as Incheon-New York increasing 36.6% to 354,000 won. October surcharges are based on average jet-fuel prices from August 16 through September 15, making further increases appear highly likely after the latest oil rally. Higher fares could weaken demand while overseas travel remains below pre-pandemic levels: July outbound travelers totaled 2,419,457, down 0.7% from a year earlier and equal to 91.6% of July 2019. Analysts and industry sources expect airline profitability pressure to intensify from the third quarter onward if high oil prices persist.