Coercion without Invasion: Trump, Greenland, and the Erosion of International Law
By Janakan Muthukumar
Published on 16 May 2025
Introduction
In a recent and troubling development in global affairs, U.S. President Donald Trump has once again revived his ambition to acquire Greenland—this time with a sharper, more coercive tone. What was once presented as a transactional real estate proposition has morphed into a narrative of entitlement and strategic necessity. In March 2025, Trump publicly declared that the U.S. will ‘go as far as we have to go’ to bring Greenland under its control. His subsequent claim that ‘Greenland must be ours’ evokes unsettling historical parallels, prompting comparisons to Saddam Hussein’s rhetoric before Iraq’s invasion of Kuwait in 1990. These declarations are not mere bluster. Accompanied by strategic gestures, they reflect a deliberate shift in posture—from diplomatic interest to geopolitical coercion.
Vice President JD Vance’s high-profile visit to the Pituffik Space Base, a U.S. military installation in Greenland, further underscores the seriousness of the administration’s messaging. Greenland’s Prime Minister, Mute Egede, condemned the visit as ‘very aggressive American pressure against the Greenlandic community’ and called for international scrutiny. The symbolism of the visit—amid renewed claims of entitlement—amplifies perceptions of pressure rather than partnership. Given the structural power imbalance between the U.S. and Denmark (Greenland’s administering state), the signals point to a form of strategic imposition.
Greenland’s geostrategic significance is well-established. It sits at the intersection of Arctic shipping lanes, missile defense systems, and natural resource claims. However, its legal status is equally settled. Landmark rulings, such as Island of Palmas (1928), Clipperton Island (1931), and Legal Status of Eastern Greenland (1933), demonstrate that sovereignty over remote or sparsely populated territories can be maintained through peaceful, uncontested administration in the absence of a superior claim. In the 1933 case, the Permanent Court of International Justice upheld Denmark’s title to Greenland despite minimal physical control, given the absence of competing sovereign claims. These precedents remain relevant in the Arctic context.
Yet sovereignty in legal terms is no longer merely a question of state-to-state claims. Modern international law increasingly recognizes that sovereignty must also account for the rights of Indigenous populations. Greenland is home to a distinct Indigenous Inuit population, whose status and agency are critical to any discussion of its future. Thus, while Denmark’s sovereign claim may be legally secure, any future arrangement concerning Greenland’s status would necessarily engage the right to self-determination as articulated in Article 1 of the International Covenant on Civil and Political Rights (‘ICCPR’) and reinforced by the United Nations Declaration on the Rights of Indigenous Peoples. For instance, Article 32 affirms that Indigenous peoples have the right to free, prior, and informed consent in matters affecting their lands, territories, and resources. Denial of this agency would not only undermine domestic democratic processes but also violate international legal protections against third-party sovereign erosion.
Against this backdrop, President Trump’s recent rhetoric not only overtly challenge the legal foundations governing territorial integrity through coercive language but also seeks to maneuver around them. His statements such as ‘we need Greenland for national security and international security,’ and ‘we have to be there,’ reflect a calculated effort to justify territorial ambition through a security lens, casting it as an imperative rather than a negotiation. While international law allows states to express political interests, public declarations by a head of state carry legal significance, especially when they signal intent to act in ways that may clash with other states’ rights under international law. Trump’s earlier remarks before the US Congress that the US would acquire Greenland ‘one way or the other,’ along with his recent refusal to rule out the use of military force to annex the territory, further amplifies these concerns. Together, these statements exemplify a broader trend: the rising use of coercive diplomacy as a substitute for lawful negotiation, blurring the lines between political rhetoric and violation of international law.
This post argues that such conduct, while falling short of being an act of aggression, it challenges fundamental tenets of international law. It weaponizes structural asymmetries, constrains sovereign discretion, and distorts the lawful processes through which territorial consent is expressed. In doing so, it exposes not only an enforcement gap but also a deeper normative ambiguity surrounding non-forcible coercion in international legal practice. This weaponization of structural asymmetry is precisely what distinguishes coercion from diplomacy: the latter invites, while the former compels.
The legal threshold for coercion requires more than rhetoric or stated intent—it demands evidence of a tangible impairment of sovereign discretion. In this case, Denmark and Greenland have been placed in a position where any future rejection of the US overtures may trigger diplomatic reprisal, economic pressure, or strategic marginalization. The coercive effect lies not in one specific act, but in the cumulative environment created—where the freedom to say no becomes legally compromised. This erosion of sovereign agency, even without a formal demand or military maneuver, aligns with the functional tests articulated in both the jurisprudence of the International Court of Justice (‘ICJ’) and is reflected in broader interpretations of coercion under international law.
Legal Framework and the Grey Zone of Coercion
The post-World War II legal order, codified in the United Nations Charter, prohibits certain forms of coercion by states. Article 2(4) of the Charter prohibits the use of force and the threat of force against the territorial integrity or political independence of any state – a rule recognized as jus cogens and binding on all states. Originally framed at deterring military aggression, the provision has been interpreted to include not only kinetic force but also threats that credibly imply such force.
The principle of non-intervention—embedded in customary international law and elaborated in the 1970 Declaration on Friendly Relations—prohibits states from intervening in the internal or external affairs of another state, particularly where coercive methods are used to affect decisions within a state’s domaine réservé. This prohibition applies regardless of whether force is involved.
In Nicaragua v. United States (1986), the ICJ found that U.S. support for Contra rebels constituted an unlawful intervention, even though there was no formal declaration of war. Similarly, in Congo v. Uganda (2005), the ICJ held that Uganda’s military and political activities in the Democratic Republic of Congo (‘DRC’) violated both the prohibition on force and the DRC’s political independence.
A third and more contested category is non-forcible coercion, which refers to actions that do not involve military force or other forms of pressure such as economic or political sanctions but may nonetheless undermine a state’s sovereignty. The legal status of such acts is unsettled: one may argue they fall under the umbrella of prohibited intervention, while others maintain that they remain lawful unless they rise to the level of force or impermissible intervention. This blurred legal boundary—the so-called ‘grey zone’—raises questions about how international law responds to subtle yet strategic efforts to erode a state’s autonomy.
This piece recognizes Trump’s claims as a form of non-forcible coercion. As part of this broader category, it defines Trump’s approach as strategic coercion—a constellation of acts including rhetoric, symbolic gestures, and embedded power asymmetries—that cumulatively erode a state’s sovereign discretion without crossing the formal threshold of force under Article 2(4) of the UN Charter.
While the global legal status of non-forcible coercion—particularly strategic coercion—remains ambiguous, regional frameworks have already moved toward clearer prohibitions. The Charter of the Organization of American States (‘OAS Charter’), for instance, explicitly bans intervention ‘or any reason whatever,’ while African Union norms similarly emphasize sovereignty and non-interference. These examples not only demonstrate how regional orders are reinforcing legal protections against subtle encroachments on sovereignty in the absence of global consensus, but also reflect deeper debates within international legal scholarship—particularly among Global South scholars and in state practice—about the boundaries between lawful influence and unlawful coercion.
Some may contend that political pressure is intrinsic to diplomacy, and that powerful states routinely exert influence to shape outcomes. However, international law distinguishes influence from coercion: the former allows for negotiation and preserves the agency of the other party; the latter seeks to eliminate it. This distinction becomes critical under conditions of asymmetrical power. As the ICJ held in its Advisory Opinion on the Wall, any threat of force contrary to the purposes and principles of the UN Charter is unlawful, affirming that international law protects not only territorial boundaries but also the sovereign discretion of states. UN General Assembly Resolution 3314 (1974), while focused primarily on armed force, its drafting history and commentaries similarly suggest that manifest threats attributable to a state’s leadership can constitute aggression. In this light, President Trump’s remarks—though falling short of an explicit threat—blur the line between persuasion and pressure. As noted above, when such rhetoric emanates from a head of state in a context of strategic dominance, it carries legal implications that move beyond campaign bluster into the realm of potential coercion under international law.
In additional to this, there is also the question of whether Trump’s statements, beyond being acts of non-forcible coercion, could also meet the threshold of a prohibited threat of force under Article 2(4) of the UN Charter. The ICJ in the Nuclear Weapons Advisory Opinion emphasized that threats are unlawful when the use of force they imply would itself be unlawful. In this context, Trump’s assertion that the U.S. ‘will go as far as we have to go’ and when he was asked whether he would rule out using force against the territory. ‘I don’t rule it out. I don’t say I’m going to do it, but I don’t rule out anything’ in acquiring Greenland may suggest a latent threat. However, absent a clear ultimatum, explicit military contingency, or conditional demand, this rhetoric likely does not satisfy the threshold for a threat of force, as analysed by Myres McDougal and Florentino Feliciano, Paul Lauren, Todd Sechser, and Mohamed Helal. Instead, it occupies an ambiguous middle ground—suggestive but not actionable—further reinforcing the importance of legal scrutiny for forms of coercion that fall below this threshold but still impair sovereign autonomy.
Seen through a broader lens, Trump’s approach to Greenland also exemplifies a pattern evident in other geopolitical contexts. Much like China’s strategic ambiguity regarding Taiwan or Russia’s phased encroachment into Crimea, the U.S. posture reflects an effort to recalibrate territorial expectations through cumulative acts of assertion rather than direct confrontation. These analogies highlight how coercive diplomacy increasingly operates through a series of incremental pressures—leveraging ambiguity and asymmetry—to achieve geopolitical aims without triggering outright conflict.
Legal Adaptation in the Grey Zone
The Greenland episode exposes not only a troubling policy trajectory but a systemic blind spot in the architecture of international legal enforcement. While the existing framework robustly addresses aggression, it remains underdeveloped in confronting coercion that is cumulative, ambient, and rhetorical. Modern coercive diplomacy often operates below traditional legal thresholds, exploiting power asymmetries and institutional inertia to shape sovereign outcomes without formal breaches. This ambiguity demands clearer legal doctrine and enforcement tools.
First, legal doctrine must begin by recognizing that coercion today is often structural, not shock-based. Strategic dominance and sustained political signaling may impair autonomy as effectively as explicit threats. Jurisprudence from above-mentioned ICJ affirms that interference becomes unlawful not only when force is used, but when it deprives a state of its freedom to act in matters within its sovereign domain. These rulings offer a legal foundation for treating cumulative political coercion as a form of impermissible intervention.
Second, the principle of free consent enshrined in Article 52 of the Vienna Convention on the Law of Treaties 1969 (‘VCLT’) should inform broader assessments of international conduct. While the provision formally applies only to treaties concluded under the threat or use of force, its underlying logic—that valid consent must be free from any form of coercion—raises important questions about the legitimacy of state conduct in asymmetrical power relationships. Specifically, international law must evolve to recognize that political pressure aimed at securing territorial concessions, even absent open military force, may equally render such agreements void or legally invalid.
Third, the development of new institutional tools is necessary. The EU’s Anti-Coercion Instrument (ACI), though originally crafted to address trade-related pressure, provides a replicable model. It enables targeted countermeasures in response to coercive practices that interfere with sovereign decision-making. ACI-type frameworks could be adapted within the UN system or regional organizations, offering legal avenues for states to respond to non-military coercion with lawful, proportionate resistance.
Fourth, international legal institutions, particularly domestic courts, regional human rights tribunals, and treaty-monitoring bodies, must more assertively operationalize the duty of non-recognition. This principle, developed in the Namibia Advisory Opinion and codified in Articles 41 and 42 of the Draft Articles on Responsibility of States for Internationally Wrongful Acts, requires states not to recognize territorial acquisitions resulting from breaches of peremptory norms. If the U.S. were to formalize its claim over Greenland through coercive means, a coordinated non-recognition response would be not merely symbolic but a legal obligation. It would serve as a collective firewall against the normalization of unlawful territorial change.
Fifth, these tools must be supported by normative clarity. Instruments like the OAS Charter, which prohibits intervention ‘for any reason whatever’ in another state’s affairs, and the Rome Statute’s Article 8 bis, which considers the ‘character, gravity, and scale’ of coercive conduct in its definition of aggression, underscore a shared legal logic: coercion, in all its forms, threatens the international legal order. Although Trump’s conduct falls short of criminal aggression, it squarely fits within this broader framework of legal concern.
While some may argue that Trump’s statements are too vague or aspirational to amount to prohibited coercion, international law must be anticipatory, not merely reactive. Sovereignty is rarely lost in a single moment; more often, it is steadily eroded—through rhetorical pressure, structural dependency, and strategic conditioning. Power framed as inevitability should still be scrutinized under law. Meaningful legal constraint also requires renewed doctrinal engagement with coercion in its modern forms through normative clarifications, such as the General Comment No.12 from the Human Rights Committee affirming that coercive diplomacy targeting autonomous territories implicates the right to self-determination under Article 1 of the ICCPR. Together, these efforts would help ensure that legal norms evolve to meet the challenges posed by ambient and accumulative coercion—before they are rendered obsolete by strategic ambiguity.
The Greenland case is not a diplomatic aberration; it is a legal stress test for the modern international order. The challenge ahead is not to reinvent foundational principles, but to interpret and apply them with greater clarity and consistency. Sovereignty, non-intervention, and territorial integrity cannot function merely as reactive doctrines triggered by visible breaches. They must evolve into anticipatory legal tools—capable of identifying and resisting the subtler, cumulative forms of coercion that erode consent without crossing conventional thresholds. In a world where power often operates through implication rather than invasion, international law must meet strategic subtlety with legal precision.
To that end, the Trump administration’s coercive rhetoric concerning Greenland—if left unchallenged—risks normalizing a mode of diplomacy that undermines the legal foundations of territorial integrity. While falling within the grey zone, such conduct is not without consequence. International legal institutions and states must be prepared to assert the principle of non-recognition, condemn coercive acquisition strategies, and reaffirm the rights of sub-state peoples to self-determination. This includes invoking legal forums, issuing declaratory statements, and embedding clear normative red lines in alliance-based diplomacy. Without a coordinated legal and political response, the erosion of territorial norms may proceed not through force, but through precedent.
Janakan Muthukumar is a Ph.D. student in the Department of Law and Legal Studies at Carleton University and a Visiting Scholar at Global Affairs Canada. His doctoral research examines the role of international law in shaping foreign policy on weapons of mass destruction. His work spans international law and ethics, cybersecurity, and foreign policy.