Korean Air's CEO, Yang Ho Cho, said the move would help "reinforce Incheon airport's position as a major international hub in North East Asia and support the growth of Korea's aviation industry." And more broadly, the international picture for U.S. airlines could grow more complicated. The U.K. on Wednesday formally declared its intent to leave the European Union following a vote to do so last summer, potentially jeopardizing the airlines' "Open Skies" agreements in the area. Meanwhile, President Trump's second attempt at a travel ban remains tied up in federal court. Among more domestic-focused carriers, Southwest Airlines ( LUV ) stock fell 1.3%, Alaska Air Group ( ALK ) 2.1% and Spirit Airlines ( SAVE ) 0.9%. RELATED: What The New Travel Ban Means For Airlines, Travel Demand