Europe live legal updates: Trump’s attack on Britain exposes a direct assault on sovereignty

Donald Trump’s declaration that the United Kingdom’s decision to hand over sovereignty of the Chagos Islands to Mauritius is an act of “great stupidity” is not merely a provocative intervention in British foreign policy. It is a legally consequential statement that reveals the intellectual and strategic framework now driving his campaign to acquire Greenland and, more broadly, his rejection of the modern international legal system governing territory, decolonisation, military basing and alliance relations.

In a post on Truth Social, Trump asserted that Britain’s plan to transfer sovereignty over the Chagos Islands, including Diego Garcia which hosts a major United States military base, demonstrates “total weakness”. He claimed that China and Russia only respect strength, and that the United States is now “respected like never before” under his leadership. He explicitly linked the Chagos decision to what he called “another in a very long line of National Security reasons why Greenland has to be acquired”, and concluded by demanding that “Denmark and its European Allies have to do the right thing”.

These remarks must be analysed not as rhetorical excess, but as a coherent legal and strategic doctrine that collides directly with binding principles of international law, the decolonisation framework of the United Nations, the law governing military bases, and the constitutional structure of NATO.

At the core of Trump’s argument lies a fundamental misunderstanding, or deliberate rejection, of the legal status of the Chagos Islands.

The United Kingdom’s decision to transfer sovereignty to Mauritius is not an act of arbitrary generosity or strategic negligence. It is the consequence of decades of international legal pressure, culminating in authoritative determinations by the International Court of Justice and the United Nations General Assembly that Britain’s continued administration of the Chagos Archipelago constitutes a wrongful act under international law.

In its 2019 advisory opinion, the International Court of Justice concluded that the process of decolonisation of Mauritius was unlawfully incomplete when the Chagos Islands were detached by the United Kingdom in 1965. The Court held that the UK is under an obligation to bring its administration of the archipelago to an end “as rapidly as possible”. The General Assembly subsequently adopted a resolution demanding British withdrawal.

These findings are grounded in the principle of self determination, enshrined in the UN Charter and developed into a peremptory norm of international law. The forced removal of the Chagossian population to facilitate the establishment of a military base was itself a grave violation of human rights law and remains one of the most widely criticised episodes of post war colonial policy.

Britain’s decision to cede sovereignty to Mauritius therefore represents compliance with international law, not weakness. It is an attempt, however belated, to remedy an unlawful colonial arrangement that has persisted for more than half a century.

Trump’s characterisation of this process as “giving away” land “for no reason whatsoever” is legally indefensible. The reason is the obligation of a former colonial power to dismantle an illegal territorial separation and to restore the territorial integrity of a decolonised state.

Even more legally flawed is the suggestion that the presence of a United States military base on Diego Garcia creates a right of ownership or veto over sovereignty. International law draws a strict distinction between sovereignty over territory and rights of military use.

Military bases on foreign soil operate through bilateral or multilateral agreements, not through territorial control. The United States base on Diego Garcia exists because the United Kingdom granted basing rights. Once sovereignty transfers to Mauritius, those rights can be preserved through a new agreement between Mauritius and the United States. There is no legal requirement that sovereignty remain British, nor any lawful basis for the United States to demand otherwise.

Trump’s argument implicitly advances a doctrine under which military utility overrides sovereign title. This doctrine was repudiated in 1945. To accept it would be to legitimise territorial acquisition or retention based on strategic convenience, a principle incompatible with the prohibition of conquest and the right of peoples to self determination.

The danger lies in Trump’s attempt to transpose this logic directly onto Greenland.

Greenland is a self governing territory within the Kingdom of Denmark. Denmark’s sovereignty is uncontested. Trump now argues that because Britain has agreed to comply with international law in the Chagos case, Denmark and its European allies must therefore surrender Greenland to the United States in the name of strength and security.

This is not legal reasoning. It is coercive geopolitics dressed in the language of national security.

Article 2(4) of the United Nations Charter prohibits the threat or use of force against the territorial integrity of any state. Trump’s repeated statements that Greenland will be taken “one way or the other”, coupled with his demand that European allies “do the right thing”, amount to explicit political coercion. When combined with his threats of punitive tariffs against allied states, this conduct increasingly meets the legal threshold of prohibited intervention in the internal and external affairs of sovereign states.

There is no doctrine in international law under which one state’s compliance with decolonisation obligations justifies another state’s territorial acquisition. On the contrary, the Chagos precedent strengthens the legal position of Denmark and Greenland by reaffirming that strategic interests cannot override territorial integrity or the rights of local populations.

Trump’s reference to China and Russia “only recognising strength” is also legally significant. It signals an abandonment of the rule based order in favour of a power based conception of international relations. Yet the legal system that constrains Chinese and Russian territorial claims in the South China Sea, Ukraine and elsewhere is the same system that constrains American ambitions in Greenland.

To selectively apply the law to rivals while rejecting it for oneself is the very definition of legal nihilism.

The implications for NATO are profound. The United Kingdom, Denmark and the United States are all NATO members. Greenland is NATO territory by virtue of Danish sovereignty. Trump’s assertion that Britain’s Chagos decision weakens Western security, and that Denmark must therefore surrender Greenland, places the United States in open conceptual conflict with the alliance’s foundational principles.

The North Atlantic Treaty is built on the sovereign equality of its members. It does not permit stronger states to dictate territorial outcomes to weaker ones. Nor does it authorise the acquisition of allied territory under the guise of collective defence.

If the logic articulated by Trump were accepted, NATO would cease to be a defensive alliance and would become a hierarchy in which the most powerful member reallocates territory in the name of security. Such a transformation would destroy the legal personality of the alliance and render its treaty framework meaningless.

Trump’s invocation of Diego Garcia also ignores the reality that the base has functioned for decades without US sovereignty over the territory. The same is true of hundreds of American bases worldwide. Legal ownership is not a prerequisite for military effectiveness. It is, however, a prerequisite for lawful international order.

From a British legal perspective, Trump’s remarks amount to a direct attack on the UK’s compliance with international judicial authority. By condemning Britain for implementing the findings of the International Court of Justice, he is effectively asserting that adherence to international law is a strategic liability.

If that proposition were to prevail, the authority of international courts would collapse. States would be incentivised to disregard binding norms whenever compliance conflicted with perceived security interests. The result would be a return to the legal conditions of the nineteenth century, when territory was allocated by force and diplomacy was merely the management of conquest.

There is also a human dimension absent from Trump’s formulation. The Chagossian people were expelled from their homeland to create the Diego Garcia base. Their right of return and their right to restitution are central to the legal case against British administration. Greenland’s population likewise holds the right to self determination. They are not strategic assets to be exchanged between great powers.

Trump’s statement that the UK’s decision is “another in a very long line of National Security reasons why Greenland has to be acquired” therefore represents a radical inversion of international law. It treats the lawful correction of a colonial injustice as proof that territorial acquisition is necessary elsewhere.

In reality, the opposite is true.

The Chagos process demonstrates that even powerful states are bound by legal duties to relinquish unlawfully held territory. It affirms that strategic utility does not defeat sovereign rights. It reinforces the principle that territory is not a commodity to be traded according to military convenience.

By condemning this process, Trump reveals that his Greenland policy is not grounded in law, alliance solidarity or collective security. It is grounded in a doctrine of strength that rejects legal restraint and treats sovereignty as conditional upon military power.

This is not merely a diplomatic disagreement. It is a systemic challenge to the legal architecture that has governed international relations since the Second World War.

If the world accepts that Britain is foolish to obey the International Court of Justice, and that Denmark is obliged to surrender Greenland because the United States deems it strategically useful, then the prohibition of conquest, the right of peoples to determine their future, and the equality of states before the law become empty phrases.

The Chagos Islands and Greenland are geographically distant. Legally and symbolically, they are now bound together in a single confrontation between law and power.

The question is no longer whether Trump can be persuaded to moderate his language. It is whether the international community is prepared to defend the principle that territory is governed by law, not by the ambitions of those who possess the greatest force.