The Chinese and Japanese governments both claim sovereignty over a group of islands in the East China Sea, called the Diaoyu Islands in Chinese and the Senkaku Islands in Japanese. The dispute over the islands has become intense since the Japanese government declared the purchase of the islands from a private owner in 2012. Newspapers in the two countries have played an important role in appealing not just to domestic readers, but also to international readers on this issue. This research project aims to identify how Chinese and Japanese online newspaper editorials construct their arguments about the disputed islands in English from a linguistic perspective. To do this, the project explores text structure, evaluative language, and visual images in the editorials of the Chinese and Japanese English-medium newspapers, using genre, APPRAISAL and multimodality frameworks developed within systemic functional linguistics. This project also adopts corpus techniques for selecting the samples. A corpus of fifty editorials published between 2012 and 2016 was compiled from the Chinese newspapers and Japanese newspapers. The analysis of the data shows that the two corpora used the same micro-genre, claim, most frequently. Negative evaluations towards the opposite country were dominant in the two sets of editorials. The two corpora, however, differed in the types of expositions, varieties of evaluations, and visual resources used in the editorials. By exploring the discursive construction of the editorials in relation to contextual information, the thesis has revealed the way the discursive resources contribute to realising the ideologies behind the Diaoyu/Senkaku islands dispute. The findings contribute to our understanding of the way conflicting views can be constructed with the use of linguistic and multimodal resources in the context of online English-medium news media.