A Simple Overview of the Options for One Country Taking Over Another in International Law

All eyes seem to have been on President Trump since his election victory back in November. With his threat of tariffs now a reality and a surprising statement that Gaza could be run by the US, we have a look today at one of his other policies – taking over Greenland and the options open to the US is they chose to do so.

International law governs the relationships between nations and establishes rules for how countries can interact. The question of one country taking over another can arise in various contexts, including annexation, colonisation and occupation. This guide will outline the key options and principles involved in such actions under international law.

1. Annexation

Annexation refers to the formal incorporation of territory by one state into another. Under international law, annexation is generally considered illegal unless it occurs through consent. For example:

– Consent: If a country voluntarily cedes territory to another (e.g., through a treaty), the annexation can be recognised legally.

– Self-Determination: If a population in a specific territory seeks to join another state through a legitimate referendum, this could potentially justify annexation, although this remains a contentious area of international law.

2. Colonisation

Colonisation involves establishing control over a foreign territory and its people, often without their consent. The traditional model of colonisation is largely deemed illegal today due to principles of self-determination and sovereignty set out in documents such as the United Nations Charter. 

– Decolonisation: Former colonies now have the right to self-determination, and international law seeks to prevent any new colonisation attempts.

3. Military Occupation

Military occupation occurs when armed forces of a state take control of a territory belonging to another state, typically during or after a conflict. The laws governing military occupation are found in the Fourth Geneva Convention and customary international law.

– Legal Status: An occupying power is allowed to maintain order and security but cannot annex the territory or alter its permanent status.

– Duration: The occupation should be temporary, and the rights of the local populace must be respected.

4. Incorporation Through Force

Using force to incorporate another territory is generally prohibited under international law. The UN Charter prohibits the threat or use of force against the territorial integrity or political independence of any state.

– Exception: Self-defence against aggressive actions may justify the use of force, but this is a very narrow interpretation and requires clear evidence of an imminent threat.

5. Recognition and Non-Recognition

For any takeover to receive legitimacy, it must often be recognised by other nations. Non-recognition by the international community can lead to sanctions and diplomatic isolation.

– International Response: An occupation or annexation that violates international law will likely prompt responses such as condemnation, economic sanctions or military intervention from other nations or international organisations such as NATO.

6. Negotiated Settlements

Diplomatic negotiations can lead to agreements regarding territory, often initiated through international mediation. Peace treaties and accords can facilitate changes in sovereignty, reflecting mutual consent rather than unilateral action.

– Self-Determination: In many cases, negotiations should involve the input of affected populations to ensure that their rights and wishes are considered.

Conclusion

The options for one country to take over another are limited and highly regulated by international law. The principles of sovereignty, self-determination and the prohibition of force generally guide interactions between states. Ultimately, the legitimacy of any takeover highly depends on adherence to these principles and the recognition of the international community. As global dynamics evolve, understanding these legal frameworks remains crucial in navigating international relations.

Therefore unless the US is seeking to potentially isolate itself from its NATO allies (Greenland being a semi autonomous territory belonging to Denmark, themselves a member of NATO) it would seem the only way that a solution for Greenland will be found is by the option of negotiated settlement via diplomatic channels.

This blog was prepared by Alexander JLO’s senior partner Peter Johnson on the 28th February 2025 and is correct at the time of publication. Peter has over 40 years’ experience in the areas of Family Law, Company & Commercial, IT & Intellectual Property, Employment Law and Litigation working as a Solicitor.

Peter’s profile on the independent Review Solicitor website can be viewed here.