Chokepoint Sovereignty and Maritime Security: The Legal Regime of the Bab-el-Mandeb Strait and the Red Sea

The Red Sea and its southern bottleneck, the Bab-el-Mandeb Strait, constitute one of the most geostrategically vital and legally complex maritime corridors on the globe. Connecting the Indian Ocean via the Gulf of Aden to the Mediterranean Sea via the Suez Canal, this narrow waterway facilitates the transit of approximately ten to twelve percent of global maritime trade, including a significant portion of the world’s energy supplies. Historically dubbed the Gate of Grief due to its hazardous navigational features, the Bab-el-Mandeb has increasingly become a focal point of geopolitical friction, regional conflict, and evolving interpretations of the law of the sea. The intersection of sovereign state interests, non-state actor interventions, and the international community’s demand for uninterrupted freedom of navigation presents a critical test for the contemporary normative framework established under the United Nations Convention on the Law of the Sea (UNCLOS).

To understand the legal dynamics of this region, one must dissect not only treaty-based provisions but also the customary rules of international law, the historical outcomes of maritime boundary arbitrations, and the legal constraints governing maritime security operations. This paper examines the legal classification of the Bab-el-Mandeb, the delicate balance between the rights of transit and coastal state jurisdiction, the resolution of historical territorial disputes, and the international law governing modern security interventions in these volatile waters.

What is the legal status of the Bab-el-Mandeb Strait under international law?

The legal status of the Bab-el-Mandeb Strait is primarily governed by Part III of the United Nations Convention on the Law of the Sea, which establishes the regime for straits used for international navigation. Under international law, a strait is geographically defined as a natural waterway connecting two larger bodies of water. For a strait to fall under the specific legal regime of Part III of UNCLOS, it must satisfy both a geographical and a functional criterion. Geographically, it must connect one part of the high seas or an exclusive economic zone (EEZ) with another part of the high seas or an EEZ. Functionally, it must be used for international navigation. The Bab-el-Mandeb Strait seamlessly meets both criteria, serving as the sole maritime connection between the EEZ and high seas of the Gulf of Aden and those of the southern Red Sea.

Consequently, the applicable legal regime within the Bab-el-Mandeb is that of transit passage, as articulated in Article 38 of UNCLOS. This regime was a hard-fought compromise during the Third United Nations Conference on the Law of the Sea (UNCLOS III). Maritime powers, led by the United States and the Soviet Union, insisted on a transit regime more permissive than innocent passage as a condition for accepting the expansion of the territorial sea limit to twelve nautical miles. Because the physical width of the Bab-el-Mandeb is approximately 18 nautical miles at its narrowest point—divided by the Yemeni island of Perim into the western Large Strait (approx. 16 miles wide) and the eastern Small Strait (approx. 2 miles wide)—the entire strait falls within the overlapping territorial seas of the littoral states: Yemen, Djibouti, and Eritrea. Without the transit passage regime, these waters would be governed solely by innocent passage, significantly curtailing global maritime mobility.

The regime of transit passage guarantees all ships and aircraft the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit through the strait. Crucially, this right cannot be suspended, hampered, or impeded by the littoral states. Article 44 of UNCLOS explicitly reinforces this non-suspendability, stating that there shall be no suspension of transit passage. This is a fundamental departure from the rules governing the standard territorial sea, where coastal states may temporarily suspend innocent passage under strict conditions for security reasons.

To fully grasp this regime, it is essential to answer a critical comparative question: What is the legal difference between transit passage and innocent passage? The distinctions are profound and carry significant operational consequences for both commercial and military vessels, as summarized in the comparative analysis below:

Legal Dimension	Transit Passage (UNCLOS Part III)	Innocent Passage (UNCLOS Part II)
Submarine Navigation	Submerged transit is permitted if it constitutes the vessel's "normal mode" of operation.	Submarines must navigate on the surface and show their flag (Article 20).
Overflight Rights	Guaranteed right of overflight for civil and military aircraft.	No inherent right of overflight; sovereign airspace extends over the territorial sea.
Suspensibility	Strictly non-suspendable under any circumstances (Article 44).	Temporarily suspendable in specified areas for security purposes (Article 25(3)).
Coastal State Regulation	Limited to safety, pollution control, and prevention of fishing/smuggling (Article 42).	Broader regulatory competence regarding national security and environmental laws.
Standard of Conduct	Refrain from threat or use of force against the sovereignty of littoral states (Article 39).	Passage must not be prejudicial to the peace, good order, or security of the coastal state (Article 19).

The status of these provisions under customary international law is of paramount importance, particularly because key regional and global actors are not party to UNCLOS. For instance, Eritrea has not ratified the convention, and the United States has signed but not ratified it. Nevertheless, the International Court of Justice (ICJ) and international arbitral tribunals have consistently affirmed that the core provisions of UNCLOS regarding passage regimes reflect customary international law. In the landmark Corfu Channel Case (1949), which predated UNCLOS, the ICJ recognized the customary right of warships to pass through straits used for international navigation without prior authorization. Today, the consensus among international legal scholars is that the regime of transit passage has solidified into customary international law, binding both parties and non-parties alike, thereby ensuring a uniform legal standard for the Bab-el-Mandeb.

Maritime Boundary Delimitations and Sovereign Disputes

The geopolitical stability of the Red Sea basin is inextricably linked to the precise delimitation of maritime boundaries and the resolution of sovereignty over various offshore islands. Because the Red Sea is a narrow semi-enclosed sea, no point within the basin lies more than 200 nautical miles from a coastal state’s baseline. Consequently, the establishment of Exclusive Economic Zones (EEZs) and continental shelves requires negotiated agreements or judicial delimitations based on the principle of equity, as codified in Articles 74 and 83 of UNCLOS.

The most significant legal precedent addressing these issues in the southern Red Sea is the Yemen-Eritrea Arbitration (1998–1999), administered by the Permanent Court of Arbitration (PCA). The dispute erupted in December 1995 when armed clashes occurred between Yemeni and Eritrean forces over Greater Hanish Island, a strategically positioned island in the southern Red Sea. The conflict threatened to disrupt international shipping and destabilize the Bab-el-Mandeb region. The parties subsequently agreed to submit their dispute to a five-member arbitral tribunal, which divided the proceedings into two distinct phases: sovereignty over the islands, and maritime delimitation.

In answering the question, How did the Yemen Eritrea arbitration resolve maritime boundary disputes?, we must analyze the two-phase approach of the tribunal. In the first phase (1998), the tribunal evaluated historical claims dating back to the Ottoman Empire, Italian colonial administration, and subsequent British presence. The tribunal rejected both states' claims of ancient or immemorial title. Instead, it applied the modern international law of acquisition of territory, focusing on the actual, continuous, and peaceful display of state authority (the concept of effectivités). The tribunal concluded that Yemen had a superior legal claim to the Hanish-Zuqar archipelago, while Eritrea was awarded sovereignty over the Mohabbakah islands, which lie closer to the Eritrean coast. Crucially, the tribunal ruled that the sovereignty awarded to Yemen was subject to a "perpetual treaty regime" safeguarding the traditional artisanal fishing rights of fishermen from both nations—a notable contribution to the intersection of sovereignty and human rights in international law.

In the second phase (1999), the tribunal addressed the maritime boundary delimitation. Eritrea argued for a boundary based strictly on the equidistance principle, while Yemen contended that its islands should receive full weight, pushing the boundary westward. The tribunal adopted a balanced approach, drawing a single multi-purpose maritime boundary for the territorial seas, EEZs, and continental shelves. It applied the standard equitable principles/relevant circumstances method, first constructing a provisional median line and then adjusting it to account for geographic realities. The tribunal determined that the smaller, uninhabited islands of both states should not exert a disproportionate influence on the delimitation line. Thus, it gave only partial effect to certain islands, ensuring that the final boundary achieved an equitable result that respected the coastal configurations of both mainland territories.

"The maritime boundary must be a single line of delimitation for all purposes, constructed on equitable principles and taking into account all relevant geographic circumstances, including the presence of islands and the traditional livelihoods of local populations."

Another critical maritime boundary development occurred in the northern reaches of the Red Sea, directly impacting transit access to the entire basin: the 2016 maritime boundary agreement between Egypt and Saudi Arabia. This treaty resulted in the transfer of sovereignty over the islands of Tiran and Sanafir from Egypt to Saudi Arabia. Located at the entrance of the Gulf of Aqaba, these islands command the narrow Straits of Tiran, which provide maritime access to Jordan's sole port of Aqaba and Israel's southern port of Eilat. Under the 1979 Egypt-Israel Peace Treaty, the Straits of Tiran are recognized as an international waterway with guaranteed freedom of navigation. The transfer of sovereignty to Saudi Arabia—a state that is not a party to the peace treaty—raised complex legal questions. To preserve the regional legal equilibrium, Saudi Arabia formally committed to respecting the navigational arrangements established under the 1979 treaty, ensuring that the Straits of Tiran remain open to international transit in accordance with international law.

How does international law regulate maritime security operations in the Red Sea?

The contemporary security environment in the southern Red Sea and the Bab-el-Mandeb is characterized by severe asymmetric threats, including state-sponsored interdictions, piracy, and attacks by non-state armed groups, most notably the Houthi movement in Yemen. Since late 2023, the Houthis have launched numerous drone and missile attacks against commercial and military vessels transiting the Bab-el-Mandeb, claiming solidarity with Palestinians in Gaza. These actions have severely disrupted global trade, forcing major shipping lines to reroute vessels around the Cape of Good Hope, thereby increasing shipping costs, carbon emissions, and transit times.

The legal framework regulating maritime security operations (MSO) in response to these threats is multi-faceted, resting on the law of state responsibility, the right of self-defense under the United Nations Charter, and the international law of naval warfare. When a non-state armed group operates from the territory of a sovereign state to attack international shipping, the legal obligations of the territorial state are clear. Under customary international law, as famously articulated in the Trail Smelter arbitration and the Corfu Channel Case, every state has an obligation "not to allow knowingly its territory to be used for acts contrary to the rights of other States." However, when the internationally recognized government of a state (such as the Presidential Leadership Council in Yemen) lacks effective control over its territory due to an ongoing civil war, the enforcement of this obligation becomes practically impossible, leading to a legal and security vacuum.

To fill this vacuum, international coalitions have initiated maritime security operations, such as the U.S.-led Operation Prosperity Guardian and the European Union’s Operation Aspides. The legal basis for these operations relies heavily on the inherent right of individual and collective self-defense, as codified in Article 51 of the UN Charter. When warships or commercial vessels flying the flag of a state are subjected to armed attacks, the flag state has the legal right to use proportionate and necessary force to repel those attacks. This right was reinforced by UN Security Council Resolution 2722 (2024), which condemned Houthi attacks on merchant and commercial vessels and explicitly took note of the right of member states, in accordance with international law, to defend their vessels from attacks, including those that undermine navigational rights and freedoms.

However, the application of force must strictly adhere to the principles of necessity and proportionality under the jus ad bellum (the law governing the resort to force). While defending a ship against an incoming missile is a clear-cut case of tactical self-defense, launching retaliatory strikes against military targets inside Yemen (such as radar installations and launch sites) constitutes a strategic use of force. Legal scholars debate whether such airstrikes meet the threshold of self-defense or if they cross into reprisal operations, which are generally prohibited under international law. Proponents of the airstrikes argue they are necessary and proportionate measures to prevent ongoing, systematic attacks on international shipping, utilizing the "unwilling or unable" test regarding the territorial sovereign's ability to suppress threats emanating from its soil.

Furthermore, the operational conduct of forces in the Red Sea is governed by the jus in bello (the law of armed conflict). Although the conflict between coalition forces and the Houthi movement is classified as a non-international armed conflict (NIAC) because the Houthis are a non-state actor, the customary principles of the law of naval warfare apply. These principles are largely codified in the San Remo Manual on International Law Applicable to Armed Conflicts at Sea (1994). Key principles include:

• Distinction: Warring parties must distinguish between military objectives and civilian objects. Commercial vessels, unless they are directly contributing to the enemy's military action (e.g., carrying troops or transmitting military intelligence), are immune from attack.
• Proportionality: The collateral damage to civilian life or property resulting from an attack must not be excessive in relation to the concrete and direct military advantage anticipated.
• Feasible Precautions: Commanders must take all feasible precautions to minimize civilian harm when targeting military assets near populated coastal areas.

It is also critical to distinguish these contemporary state-sponsored and asymmetric threats from piracy. Under Article 101 of UNCLOS, piracy is defined as any illegal act of violence, detention, or depredation committed for private ends by the crew or passengers of a private ship or aircraft on the high seas or in a place outside the jurisdiction of any state. Because the Houthi attacks are politically motivated, state-aligned, and frequently occur within the territorial sea of Yemen, they do not meet the strict legal definition of piracy under international law. Instead, they constitute maritime terrorism or unlawful acts against the safety of maritime navigation, which are governed by the 1988 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (SUA Convention). The SUA Convention obligates contracting states to either extradite or prosecute individuals who seize control of a ship by force or perform acts of violence against persons on board.

Freedom of Navigation versus Coastal State Jurisdiction

The permanent tension in the law of the sea is the friction between the common interest of the international community in keeping maritime transit lanes open and the particular interest of coastal states in protecting their security, environment, and economic resources. In the narrow waters of the Red Sea and the Bab-el-Mandeb, this tension is magnified. Under UNCLOS, coastal states possess sovereign rights and jurisdiction over their territorial seas, contiguous zones, and EEZs, but these rights are strictly circumscribed to prevent them from choking international commerce.

In analyzing this friction, we must address another critical question: Can a coastal state suspend the right of transit passage? The unequivocal answer under international treaty law is no. As established in Article 44 of UNCLOS, transit passage through straits used for international navigation cannot be suspended, hampered, or impeded by the littoral states. Even if a littoral state is engaged in an armed conflict, it cannot lawfully suspend this right for neutral vessels. This absolute prohibition is designed to prevent regional conflicts from paralyzing global trade networks. If a littoral state attempts to close the Bab-el-Mandeb or restrict transit, such actions constitute a violation of international law, authorizing affected states to take lawful counter-measures, including diplomatic, economic, and defensive military actions.

However, this does not mean coastal states are devoid of authority. UNCLOS grants littoral states limited regulatory competence within straits under Article 42. Littoral states may adopt laws and regulations relating to transit passage concerning:

1. The safety of navigation and the regulation of maritime traffic, including the designation of sea lanes and traffic separation schemes (TSS) approved by the competent international organization (the International Maritime Organization, or IMO).
2. The prevention, reduction, and control of pollution, by giving effect to applicable international regulations regarding the discharge of oil, oily wastes, and other noxious substances.
3. With respect to fishing vessels, the prevention of fishing, including the stowage of fishing gear.
4. The loading or unloading of any commodity, currency, or person in violation of the customs, fiscal, immigration, or sanitary laws of the strait States.

Such laws, however, must not discriminate among foreign ships and must not have the practical effect of denying, hampering, or impairing the right of transit passage. If a foreign vessel violates these lawful regulations, the coastal state may take enforcement measures, but these measures are restricted. For warships and other government vessels operating on non-commercial service, the principle of sovereign immunity applies (Articles 32, 95, and 96 of UNCLOS). A coastal state cannot board, seize, or arrest a foreign warship; the only recourse is to require the vessel to leave the territorial sea immediately and hold the flag state liable for any damage caused.

Environmental jurisdiction in the Red Sea is particularly critical due to the basin's unique, highly sensitive coral reef ecosystems. The Red Sea is designated as a Special Area under Annex I (oil pollution prevention) and Annex V (garbage pollution prevention) of the International Convention for the Prevention of Pollution from Ships (MARPOL). This designation imposes stricter discharge standards on all transiting vessels. The enforcement of these standards, however, requires stable and functional coastal state governance.

A stark reminder of the intersection between environmental vulnerability and political instability was the crisis of the FSO Safer. A decaying, single-hulled floating storage and offloading unit moored off the coast of Yemen, the FSO Safer held over 1.1 million barrels of crude oil. Abandoned in 2015 due to the Yemeni civil war, the vessel’s structural integrity degenerated to the point of imminent rupture, threatening an ecological and humanitarian catastrophe that would have closed the Bab-el-Mandeb and devastated the entire Red Sea marine environment. The legal resolution of this crisis required complex, multi-lateral negotiations led by the United Nations. Because the Houthis controlled the physical territory where the vessel was located, while the internationally recognized government held the legal sovereignty, standard treaty-based enforcement mechanisms under UNCLOS Part XII (Protection and Preservation of the Marine Environment) were ineffective. The successful salvage operation in 2023—which involved transferring the oil to a replacement vessel—underscored that protecting the marine environment in conflict zones requires pragmatic, ad-hoc legal diplomacy that transcends rigid state-centric paradigms.

The Geopolitical Horizon of Maritime Governance

The future of maritime security and legal order in the Bab-el-Mandeb and the Red Sea will be shaped by the shifting alignments of global powers and the growing militarization of the region. Djibouti has become a microcosm of this geopolitical competition, hosting military bases for the United States, France, Japan, Italy, and China—marking China's first overseas military support base. The presence of multiple foreign navies in close proximity within a narrow maritime chokepoint increases the risk of operational miscalculations and highlights the necessity of robust conflict-deconfliction mechanisms.

Furthermore, the rise of regional initiatives, such as the Council of Arab and African Coastal States of the Red Sea and the Gulf of Aden (established in 2020 by Saudi Arabia), reflects an effort by littoral states to assert greater collective ownership over the region's security and environmental governance. However, the exclusion of key actors—such as Ethiopia (a landlocked state with vital transit interests in Djibouti), Eritrea, and Israel—limits the council’s capacity to serve as a comprehensive security architecture. For these regional frameworks to be effective and legally resilient, they must align with the inclusive, universally accepted principles of UNCLOS, balancing the sovereign rights of coastal states with the non-negotiable global interest in the freedom of navigation.

Ultimately, the legal regime of the Bab-el-Mandeb and the Red Sea is not a static set of rules but a dynamic, contested arena where international law is continuously interpreted, applied, and occasionally challenged. The stability of global maritime trade depends on the preservation of the transit passage regime, the peaceful resolution of boundary disputes, and the lawful, proportionate deployment of maritime security operations. As asymmetric threats and geopolitical rivalries continue to test the limits of public international law, the enduring challenge will be to maintain the rule of law over the rule of force in these critical, historical waters.