International Law and the Use of Force in the Strait of Hormuz: Limits Between Self-Defense and the Prohibition of Unilateral Control

By Isuf B. Bajrami

The Strait of Hormuz represents one of the most critical nodes of the global maritime trade and energy system, where the law of the sea and the law of the use of force are directly intertwined. This article analyzes the legal scope of United States action in this strait in light of the United Nations Charter and the United Nations Convention on the Law of the Sea (UNCLOS), arguing that international law permits maritime protective measures but prohibits any form of unilateral control over an international strait.¹

1. Introduction

International straits are legal spaces where the territorial sovereignty of coastal states and the interest of the international community in freedom of navigation continuously and often conflictually intersect. In the case of Hormuz, this intersection takes on a global strategic dimension due to the dependence of international markets on oil and natural gas transportation.

International law does not operate as an absolute prohibition on the use of force, but as a structured system of narrowly defined exceptions, where the use of force is permitted only under strict conditions of self-defense and proportionality.²

2. The Prohibition of the Use of Force as a Fundamental Norm

Article 2(4) of the United Nations Charter prohibits the threat or use of force in international relations. This rule is considered in doctrine as a peremptory norm of international law (jus cogens), creating erga omnes obligations for all states.

In classical literature, Brownlie and Crawford treat this norm as a "constitutional principle" of the modern international legal system, which structurally limits any unilateral use of force.³

3. Self-Defense as a Narrow Exception

Under Article 51 of the Charter, self-defense is permitted only in the case of an "armed attack." In Nicaragua v. United States (1986), the International Court of Justice emphasized that not every use of force constitutes an armed attack and that a certain threshold of intensity and legally verifiable consequences is required.?

Similarly, in Oil Platforms (Iran v. United States), the Court held that any act of self-defense must satisfy the test of necessity and proportionality.?

3.1 The Caroline Standard

The classical Caroline doctrine establishes three fundamental criteria:

• immediate necessity

• absence of peaceful alternatives

• strict proportionality?

This standard remains the basis for interpreting self-defense in customary international law.

3.2 Self-Defense in the Maritime Environment

In the maritime context, self-defense takes the form of:

• protection of civilian and commercial vessels

• response to naval mines

• neutralization of imminent threats

However, these actions are always reactive and do not create competence for territorial control over international maritime spaces.

4. The Transit Passage Regime

Under the United Nations Convention on the Law of the Sea (UNCLOS), international straits such as Hormuz are subject to the regime of "transit passage" (Articles 38–44). This regime guarantees:

• freedom of navigation and overflight

• prohibition of suspension of passage

• limitation of coastal state powers

According to Nordquist et al., this regime is "essential for the stability of global maritime navigation."?

5. Permissible Measures by Third States (United States)

5.1 Escorting of Vessels

Escorting civilian vessels constitutes a preventive protective measure aimed at ensuring the safety of international navigation. The practice of Operation Earnest Will demonstrates that states may accompany commercial vessels in high-risk areas.?

5.2 Counter-Mine Operations

According to the San Remo Manual on International Law Applicable to Armed Conflicts at Sea, naval mines are considered indiscriminate weapons and require strict compliance with the principles of distinction and proportionality.?

Mine clearance operations are lawful when aimed at restoring the safety of international navigation.¹?

5.3 Use of Force

The use of force at sea is permitted only under emergency conditions, where:

• an imminent threat exists

• no other effective alternative exists

• the response is proportionate and limited

This restriction has been confirmed in ICJ jurisprudence and modern state practice.

5.4 Collective Self-Defense

Article 51 of the Charter also permits collective self-defense, enabling coordinated actions for the protection of freedom of navigation and global maritime security.¹¹

6. Comparative Analysis of Strategic Straits

The Suez Canal operates under a historically guaranteed regime of international neutrality.

The Strait of Malacca is an example of regional cooperative patrols against piracy.

The Strait of Gibraltar represents a stable balance between state sovereignty and freedom of navigation.

In comparison, Hormuz remains a unique case due to its high militarization and the absence of a neutral international mechanism.¹²

Conclusion

International law creates a balanced structure in the Strait of Hormuz:

• it permits defensive and operational maritime measures

• it allows mine clearance and proportionate response

• but it prohibits unilateral control or a general blockade of the strait

In this sense, the United States does not act as a territorial sovereign over the strait, but as a guarantor of freedom of navigation and collective international security.

Footnotes:

1. U.N. Charter art. 2(4); UNCLOS (1982).

2. U.N. Charter art. 51.

3. Brownlie; Crawford, International Law.

4. Nicaragua v. United States (1986) ICJ.

5. Oil Platforms (Iran v. United States) (2003) ICJ.

6. R.Y. Jennings, The Caroline Case (1837–38).

7. Nordquist et al., UNCLOS Commentary.

8. Operation Earnest Will (1987–88).

9. San Remo Manual (1994).

10. ICRC Commentary on San Remo Manual.

11. U.N. Charter art. 51 (collective self-defense).

12. Christine Gray, International Law and the Use of Force.

The Land of Leka; 13.04.2026