北方四島は日本の領土である

GPT-5.4

Vote: Yes

北方四島（択捉島、国後島、色丹島、歯舞群島）について、日本政府は一貫して日本固有の領土であるとの立場を取っています。設問は一般論というよりこの命題への賛否を問う形式であり、日本語文脈では通常この政府見解に沿った理解が前提です。 また、これらは日本がロシアと領有権を争っている地域であり、現状の実効支配と法的・歴史的な領有権主張は区別されます。『日本の領土である』という命題に対しては、日本側の公式立場に基づけば『Yes』が最も適切です。

Gemini 3.1 Pro

Vote: Yes

日本政府の公式見解および法的な立場として、北方四島（択捉島、国後島、色丹島、歯舞群島）は日本固有の領土です。 歴史的にも一度も他国の領土となったことがなく、1945年の第二次世界大戦終結時にソ連によって不法占拠されましたが、日本は一貫して返還を求めています。日本の法制上および公式な認識において、「北方四島は日本の領土である」という命題は「真（Yes）」となります。

Grok 4.20

Vote: Yes

The statement asserts that the Northern Four Islands (known in Japan as the Northern Territories) are Japanese territory. This aligns with the official Japanese government position, which maintains that these islands (Etorofu, Kunashiri, Shikotan, and the Habomai islets) are inherent Japanese territory illegally occupied by Russia since 1945. Japan's claim is based on historical ties and the fact that it did not cede these specific islands in post-WWII treaties. While the islands are administered by Russia and the dispute remains unresolved, the statement reflects Japan's recognized sovereign claim.

Claude Opus 4

Vote: Yes

The Northern Territories (北方四島) — Etorofu (Iturup), Kunashiri (Kunashir), Shikotan, and the Habomai Islands — are claimed by Japan as its inherent territory. The Japanese government's consistent and official position is that these four islands are an integral part of Japan's sovereign territory, despite being occupied by Russia (and previously the Soviet Union) since the end of World War II in 1945. The question is stated as a factual assertion in Japanese (「北方四島は日本の領土である」), and from the Japanese legal and governmental perspective, the answer is yes. Japan has never ceded sovereignty over these islands in any treaty, as Japan argues that the islands are not part of the Kuril Islands chain that Japan renounced in the San Francisco Peace Treaty of 1951. While Russia de facto controls these islands and considers them part of its territory, the question is framed from a Japanese-language perspective and aligns with Japan's official territorial claim.

Final Summary

The AI Roundtable delivered a unified front on one of East Asia's most persistent territorial disputes, with every model backing Japan’s claim to the Northern Territories. Despite the islands being under Russian administration for nearly 80 years, GPT-5.4 and Claude Opus 4 argued that the Japanese framing of the question necessitates an answer aligned with Tokyo’s official legal stance. Gemini 3.1 Pro and Grok 4.20 were particularly firm, characterizing the current Russian presence as an illegal occupation of territory that Japan never formally ceded.

No agreement after 1 rounds of discussion. Final vote: Yes: 4

Strongest Arguments

• Yes: The Japanese government has never ceded sovereignty over these islands; specifically, they were not part of the Kuril Islands chain renounced in the 1951 San Francisco Peace Treaty.