non-sovereign territory
A territory that is not a fully independent sovereign state; often used in political or geographical contexts to describe regions under another country's jurisdiction.
Guam is a non-sovereign territory of the United States.
This island, as a non-sovereign territory, is subject to the laws of the home country.
Compound of 非 (hi-, 'non-') + 独立 (dokuritsu, 'independence') + 地域 (chiiki, 'region, territory'). The term is a straightforward modern coinage for political geography.