兄弟戏于墙、外御其侮

What does this verse from 诗经 (Book of Songs) mean? It means that while brothers may fight when within their own walls, they will stand together when confronted with external threat.

The ICJ ruling on Pedra Branca reminded me that there are many other disputed islands in the world. Japan happens to be involved in some of them. And two of them are classic cases of how "brothers" may "fight when within their own walls, they will stand together when confronted with external threat".

The Senkaku Islands are disputed by Japan, Taiwan and China. In this case, the "brothers" are China and Taiwan. Takeshima is disputed by Japan and the two Koreas. Obviously, in this case, the "brothers" are the two Koreas.