Peter Lee's Asia Times article makes an interesting point regarding Japan's claims to various islands and island chains--most heatedly the Senkaku/Diaoyu Islands in the East China sea with China/Taiwan, but also Dokdo/Takeshima with South Korea and the Kuril Islands with Russia. Japan is laying claim to three different island groups with three different nations--Japan's only maritime neighbours, excluding Micronesian states--for three different reasons rather than settling on a consistent rationale for defensible frontiers. The foreign policy implications of the muddle for Japan are significant, inasmuch as Japanese claims to islands claimed--arguably with greater justice--by the South Korea and the Taiwan that are Japan's only plausible allies keeps Japan from such an alliance. (The fact that the claims bring Taiwan especially but also South Korea closer to China doesn't help, either.)
Japan's claim to incontestable sovereignty over the islands goes back no further than its seizure, together with Taiwan and the Ryukyu Islands, from the Qing empire in the 1895 Sino-Japanese War, and not being forced to give them back in the post-World War II muddle.
The "spoils of war" argument, aka we got 'em and by golly we're gonna keep 'em approach, is an awkward one for Japan. It would dearly like to get back four islands on the southern end of an archipelago stretching between the Kamchatka Peninsula and Hokkaido, which are now occupied by Russia as heir to the Soviet Union's spoils of war.
The short form of this imbroglio is the "Kurile Islands dispute", but the two southernmost islands are more Hokkaido-esque, and Russia has signaled a willingness to give them up. The two more northerly islands are bona fide members of the Kurile chain. Russia wants to keep them. Japan wants them. Awkwardly for Japan, in 1956 it promised to surrender its claims to these two islands if a formal peace treaty were concluded.
Given this unfavorable position, Japan must contest the "spoils of war" argument and rely on emotive, historical claims to the islands - the exact opposite of its position on the Senkaku/Diaoyu Islands.
The "exercised sovereignty" argument also provides no comfort to Japan in its dispute with South Korea over the Dokdo Islands (Takeshima to the Japanese). After the conclusion of World War II, the United States supported the historical Japanese claims to the islands but declined to put their defense within the scope of the US-Japan Joint Security Treaty.
Since 1991, the main island has been home to a family of South Korean octopus fishermen and about three dozen Republic of Korea Coast Guard, fishery, and lighthouse personnel. President Lee Myung-bak has visited, as well as thousands of South Korean tourists who take a US$250 ferry trip to the island.
In July 2008, the administration of then-US president George W Bush acknowledged South Korean control over the islands by designating them as ROK territory.
Therefore, Japan's attempts to hold on to the Senkakus on the principle that their effective de facto control, by itself, constitutes de jure sovereignty undermines its arguments on Dokdo and the Kuriles. This inconsistency, one might assume, does not make an ironclad case to the United States to encourage a regional confrontation over Japanese dismay over Chinese pretensions to the rocks.