Making his diplomatic debut in the US this week, Yukio Hatoyama, Japan's new prime minister, lost no time in seeking to put his philosophical stamp on the international relations of the world's second largest economy.

In his New York meeting with Hu Jintao, China's president – the first in a series of bilateral summits on the sidelines of United Nations and G20 gatherings – on Monday, Mr Hatoyama called for the disputed gas-rich waters between Japan and China to be turned into a “sea of fraternity”.

Such references to Mr Hatoyama's political philosophy are a rhetorical reminder of the ramifications of Japan's historic change of government last week. Neighbours and global partners used to the diplomacy of the long- ruling Liberal Democratic party have to adjust to the priorities of Mr Hatoyama's centre-left Democrat party.