State-run China Eastern Airlines (EEA.NYSE, 600115.SH, 0670.HKG, CIAH.FRA) on Thursday announced an 18% fall in international passenger numbers month on month in September, due in part to lower Japan sales, The Wall Street Journal reported. Reduced demand comes amid a territorial tiff in the East China Sea between the two countries. Compared with last year, international passenger numbers increased only 3.5% to 641,340 in September, a stark contrast to growth on domestic routes which reached 13%. The airline handles almost one-quarter of the passenger traffic between Japan and China, and added four new Japan destinations from Shanghai earlier this year. China Eastern earns up to 35% of its profit from Japan routes, making it one of the most financially vulnerable airline should the territorial dispute concerning several islands between China and Japan continue.