Several states have recently announced their withdrawal from multilateral treaties on the grounds of national interests. For example, in 2025, Finland, Estonia, Latvia, Lithuania and Poland withdrew from the Ottawa Convention on the prohibition of anti-personnel mines, citing national security concerns. In 2026, the United States announced its withdrawal from some 66 international organisations and treaties that it claims to be contrary to its national interests. One of the fundamental principles of public international law and treaty law is that agreements must be honoured and treaties observed. Nevertheless, if there is a drastic change in the fundamental circumstances under which a treaty was agreed upon, withdrawal is possible on certain grounds. Traditionally, the threshold for invoking this exception has been high. However, recent developments suggest a shift in treaty practice towards a lower threshold for treaty withdrawals.
In this study, Frida Henriksson examines the extent to which the changing international order, both regarding security polices and treaty practice, could affect the agreements on the demilitarised status of the Åland Islands and Svalbard. Her findings show that, despite a progressive interpretation of the principle of international law justifying the termination of a treaty on grounds of changed circumstances, it is difficult to legitimise a unilateral invalidation of a demilitarisation regime on grounds of national security and state interests. This is due to the connection between the purpose of demilitarisation and the shared expectation of the international community to maintain peace in areas of high strategic interest and to ensure the stability of treaty regimes. The author concludes that invoking national security and changed circumstances as grounds for invalidating the demilitarisation regimes of the Åland Islands and Svalbard does not currently have sufficient legal support.
Frida Henriksson is a graduate (2026) from the Åbo Akademi University Master’s Degree Programme in International Law and Human Rights. The study is based on her master’s thesis in public international law. It is published in the Institute for Human Rights Working paper series which presents contributions of scholarly interest addressing a broad range of international issues.
