International straits, by way of geography—resulting in their reference as ‘choke points’—and function, are a crucial component of the maritime domain.  This is particularly true of the Indian Ocean Region within which India holds a prime position while being surrounded by ‘choke points’ on both its eastern and western seaboards.  While these choke points are of significant strategic importance to India, they can only be comprehensively understood and entirely appreciated through a clear picture of the legal regimes that govern them.  Thus, this article endeavours to provide readers with an understanding of the geographic, functional, and legal criticality of international straits located within the IOR vis-à-vis India.

Over the last decade, both in India and globally, there has been a marked refocusing of attention towards the maritime domain, specifically towards the Indian Ocean Region (IOR) and the adjacent Pacific Ocean.  This refocusing reflects a global acknowledgement of the critical contribution of oceans to States’ growth and prosperity.  For India, this refocusing is of particular importance given its central location in the IOR, ensconced by international straits that provide military and economic access to and out of the region.  The international straits in reference here are those of Hormuz and Bab-el-Mandeb flanking India on the West and the Indonesian choke points located on the East.  In light of this, an overview of the legal regimes applicable to international straits within the IOR is imperative to understanding and appreciating the criticality of these international straits to India.[1]  In doing so, the article will begin with a definition of an international strait and its types, followed by an overview of the legal regimes applicable to straits used for international navigation as codified in the United Nations Convention on the Law of the Sea (hereinafter, UNCLOS).  Thereafter, the article will address in detail the international straits found in the IOR and the peculiarities of legal regimes applicable there.

International Straits

By definition, an international strait is a narrow waterway of limited width which is bordered by land and used by both commercial and military vessels and aircrafts for international navigation between the open seas and regions of the world.[2]  The first attempt at defining international straits was made in the 1949 Corfu Channel Case[3] at the International Court of Justice wherein the court stipulated that an international strait is a waterway that connects two parts of the high seas and is used for international navigation.[4]  This precludes man-made structures such as canals which are not considered to be straits, and are usually governed by separate agreements concluded between concerned States.[5]

In being used for navigation between different regions of the world, international straits sit at a critical junction of world geography which, in turn, can be seen to dictate navigational terms of use for both small and large countries alike.  Their geographical position contributes to their criticality as strategic straits of economic and military importance, and has resulted in their reference as ‘choke points’.  There are, in fact, seven types of international straits found around the globe[6], namely:

  • Geographic straits, characterized by a width wider than 24 nautical miles (nm), such as the Taiwan Strait.
  • Straits governed by longstanding international conventions, such as the Turkish Straits, which are governed by the 1936 Montreux Convention.
  • Straits formed between a State and its islands, such as the Strait of Messina in Italy.
  • Dead-end straits, known to connect one end of the high seas or EEZ to the territorial sea of one or more State, such as the Strait of Tiran between the Sinai Peninsula and Arabian Peninsula.
  • Straits that contain routes of similar convenience, that is, a route through the high seas or an EEZ of similar navigational and hydrographic characteristics as the strait, such as the four straits of Japan.
  • Straits used for international navigation that connect one end of the high seas or Exclusive Economic Zone (EEZ) to the other and may contain overlapping territorial seas of bordering-States, such as the Straits of Malacca and Singapore.
  • Straits found within the waters of an archipelagic State, such as those of Indonesia.

Since it is impractical, given the constrained length of this article, to address each of the abovementioned straits in detail, primary focus is retained upon the two types of straits most commonly encountered in the IOR, namely, straits used for international navigation, and straits found in archipelagic waters.

Legal Regime Applicable to Straits Used for International Navigation

            The legal regime of international straits per se is driven by navigational considerations.  This is owed, in large part, to the deliberations undertaken during the third United Nations Conference on the Law of the Sea (UNCLOS III) held between 1973 and 1982, wherein two critical arguments surfaced and were subsequently included in the 1982 UN Convention on the Law of the Sea (UNCLOS)[7].  (It is important to remember that UNCLOS III [the Conference] has the same basic acronym as UNCLOS [the Convention]).  The first was the expansion of the territorial sea from 3 nm to 12 nm, and the second was the compromise reached between naval powers and bordering-States vis-à-vis the navigation of international straits with the introduction of ‘Transit Passage’.[8]  The latter is a passage regime applicable particularly to straits used for international navigation and is governed by Part III of the UNCLOS, titled “Straits Used for International Navigation”.

India signed the UNCLOS during its adoption in 1982, and ratified it thirteen years later in 1995.  However, any discourse into the applicability of international treaty law in India is premised on the position that India has a dualist legal system, which requires the Parliament to enact legislations giving effect to the particular international treaty in the domestic sphere.[9]  Thus, even a ratified treaty will become the ‘law of the land’ only when a law is passed to that effect.[10]  Interestingly, the statute giving effect to many UNCLOS provisions was adopted by India during UNCLOS III (and well before adoption of the Convention itself) by way of the “Territorial Waters, Continental Shelf, Exclusive Economic Zone And Other Maritime Zones Act, 1976”.  Perhaps due to the absence of international straits within the Maritime Zones of India (MZI), this piece of legislation does not elaborate upon passage through international straits.  Hence, to understand the nuances of the regimes applicable to the various types of international straits, one must return to UNCLOS.

Codified in Part III of UNCLOS, international straits are afforded an independent regime which is further subdivided into that of ‘transit passage’ (Section 2) and ‘innocent passage’ (Section 3).  Where ‘transit passage’ is concerned:

  • The regime of ‘transit passage’ falls squarely between the ‘right of freedom of navigation’ and ‘innocent passage’ wherein, amongst other things, vessels and aircrafts of user-States may navigate an international strait in a continuous, expeditious, and unimpeded fashion in their normal mode of operation.[11] Although there remains a grey area with regards the precise definition of the term ‘normal mode’[12], it is widely believed that it includes submerged passage rights for submarines by virtue of usage of the phrase ‘freedom of navigation’ in Article 38.[13]  This sets ‘transit passage’ apart from ‘innocent passage’, since submerged passage of underwater vehicles is expressly prohibited in the latter.[14]  Further, vessels undertaking ‘transit passage’ must do so in compliance with established safety and environmental protection regulations as codified in the 1974 Safety of Life at Sea (SOLAS) Convention and the 1973 International Convention for the Prevention of Pollution from Ships (MARPOL), as well as regulations set by States bordering straits, formed in compliance with international standards.[15]

The regime of ‘innocent passage’ is applicable to international straits of two kinds: the first comprises those straits that lie between the high seas (or exclusive economic zone [EEZ]) and the territory of a bordering-State, and the second as formed between the mainland and islands of the bordering-State.[16]  In both cases, the right of innocent passage remains in compliance with UNCLOS Part II Section 3 on innocent passage in the territorial sea.  In innocent passage, coastal States have wide regulatory powers that extend to temporary and conditional suspension of passage rights.[17]  All such regulatory powers, with the exception of the power to suspend innocent passage, applies to this category of straits, justifying the appellation, “non-suspendable innocent passage”.

A notable distinction between the two regimes is also with regard to the status of warships.  While warships are immune to the jurisdiction of coastal States during ‘innocent passage’, they may be required to leave the territorial sea if found to be in violation of the coastal State’s rules and regulations concerning ‘passage’.[18]   However, no such power can be exercised by bordering-States where transit passage is applicable.

In addition to the above-mentioned passage-regimes, there exists a separate regime that applies to archipelagic waters: the Archipelagic Sea Lanes Passage (ASLP), which will be elaborated upon in the succeeding paragraphs, using Indonesia as an example.

Rights and Duties of User-States and Bordering-States

With regard to transit passage, Article 39 lists the circumstances under which vessels and aircraft may undertake passage in international straits wherein, ipso facto, vessels and aircrafts must proceed without delay and avoid the threat or use of force against the bordering-State.  The rights and obligations of bordering-States are listed in Articles 41 and 42 wherein bordering-States may, ipso facto, designate sea-lanes and traffic-separation schemes (TSS) as well as adopt legislation on transit passage so long as the legislation is in compliance with international standards and does not hamper the regime of passage applicable to the strait.  Such legislations could include pollution control, navigational safety, maritime traffic, etc.[19]

International Straits of Relevance to India

Maritime transport accounts for 95% of India’s international trade by volume and 65% by value,[20] much of which passes through the international straits located within the Indian Ocean.  Historically, a number of ports of India have enjoyed great positional significance vis-à-vis maritime trading routes.  They continue to do so even in contemporary times.  Even today, the bulk of India’s export and import of merchandise goods — most significantly the millions of barrels of oil and liquified natural gas — flows through one or another of the international straits of the Indian Ocean.  To the west of India, these straits include the Strait of Hormuz, the Strait of Bab-el-Mandeb, and the Mozambique Channel.  It is, therefore, hardly surprising that a rise in geopolitical tensions within the Persian Gulf (such as the recent faceoff between Iran and USA in 2019), or within the Gulf of Aden (such as the ongoing conflict in Yemen), has an immediate and profound impact upon India.  A constant endeavour to assure the security and safety of India’s merchandise trade is also the major reason for India’s careful attention to the geopolitical moves in and around international straits of regional and extra-regional State- and multi-national entities.  In this context, warship activity such as that relating to Operation AGENOR within the European-led Maritime Awareness in the Strait of Hormuz (EMASOH) initiative,[21] is as carefully monitored by India as are the game-plays of the USA or China.  The same is the case with the Gulf of Aden (at whose western extremity lies the Strait of Bab-el-Mandeb) where even “after 7 years of war, Yemen remains one of the world’s worst humanitarian crises. The violence has increased since the second half of 2021, with a marked escalation in the first quarter of 2022.”[22]

Insofar as the relevance of public international maritime law is concerned, it should be noted that at its narrowest point, the Strait of Hormuz is only about 18 nautical miles wide.  Thus, one passes through the territorial sea of either Iran or Oman while transiting, making the two countries’ approach-to and acceptability-of UNCLOS crucial.  Oman has ratified the UNCLOS, whereas UAE and Iran are signatories but have not ratified the Convention.  While the status of a signatory is distinguished from a ratifying party on the basis of the legally binding nature of ratification, it is nevertheless true that the act of signing reflects a willing recognition to uphold the principles of the Convention.  Another significant legal nuance is that even at the time of signing UNCLOS, Iran had made an interpretative declaration with respect to its understanding of certain provisions in the Convention.  The declaration clarified Iran’s application of customary international law and elaborated upon the right of coastal States to take measures to protect their security interests, reserving the power to adopt laws and regulations regarding the prior authorisation for warships that were willing to exercise the right of ‘innocent passage’ through the country’s territorial sea.[23]  In a similar fashion, Oman too subjects the passage of warships and submarines through its territorial waters to prior permission through a declaration made upon ratification.[24]  Iran’s declaration further makes it clear that it adheres to the 12 nautical mile limit that has been set for the extension of territorial waters, and it applies the principles derived from customary international law and the 1958 Convention on the Territorial Sea and the Contiguous Zone[25] in its territorial waters.[26]  However, as far as passage through international straits is concerned, Article 16 (4) of the 1958 Convention provides for ‘non-suspendable innocent passage’ similar to the 1982 UNCLOS.  Moreover, a declaration made by a State does not in and of itself constitute any variation-to or deviation-of the law (in this case, UNCLOS).  That said, it is easy to see the room for legal debate or lawfare.  This could well impact India and hence, the need to have a legal strategy, a policy-approach, and, an advocacy-plan, all in place well before any incident involving Indian entities occurs, is a pressing one.

With regard to the Strait of Bab-el-Mandeb, while the bordering-States here are Djibouti and Yemen, a general overview would reveal that this strait connects the Exclusive Economic Zones (EEZs) of a far larger number of States, which includes Sudan, Saudi Arabia, Somalia, Eritrea and Egypt in addition to Djibouti and Yemen.  The adverse impact of the ongoing conflict in Yemen has already been touched upon, and control of the strait by any of the parties to the conflict, State or non-State, would not bode well for the region in terms of both security as well as movement of international trade therein.[27]  Insofar as international navigation and the legal regime laid down by the UNCLOS goes, all concerned States, apart from Eritrea, have ratified the 1982 UNCLOS.[28]  While the applicability of the passage-regime in the Strait of Bab-el-Mandeb would appear rather straightforward — given that the strait is one used for international navigation — the same has in fact come under impending threat from the spill-over effect of the ongoing conflict in Yemen.  The strait is, in and of itself, a crucial chokepoint whose significance has been enhanced ever since the opening of the Suez Canal in 1869 and its periodic widening — including the latest (2021) project to expand parts of the Suez Canal consequent upon the grounding of the container ship, the Ever Given, which blocked the waterway for six days in March of 2021.  This project, according to the Suez Canal Authority (SCA) will be completed in July 2023.[29]

On the eastern flank of the Indian Ocean, the Indonesian choke points are of very considerable strategic significance for India.  Some 190 billion US dollar worth of India’s merchandise trade pass through the narrow (2.7 kilometres at its narrowest[30]) and relatively-shallow Straits of Malacca and Singapore, and the neighbouring straits of Sunda (situated between the islands of Sumatra and Java) and Lombok (between the islands of Bali and Lombok).  The Andaman and Nicobar island-chain provides India with geographical proximity to these international straits and enable it to monitor traffic in the region, thereby providing New Delhi with considerable political leverage.[31]  The Strait of Ombai-Wetar is another international strait that is of great military (naval) significance to India, as also to all countries that operate nuclear-powered  (SSNs) in the Indo-Pacific, since it is the only strait whose hydrography permits safe underwater transit-passage to be undertaken by such submarines.[32]  Once again, as in was the case with the international straits of western Indian Ocean, a comprehensive understanding of these straits needs to factor the legal regimes applicable therein, especially as Indonesia is an archipelagic State.  It is, in fact, the largest archipelagic State — going by definition found in Article 46 of UNCLOS — in the world.  Indonesia ratified UNCLOS in 1986 and was one of the first States to claim archipelagic status after its Independence in 1953.  However, it was only after nine years of deliberation between the predominant maritime powers of that time and the bordering-States, on the status of passage applicable to archipelagic waters that had thus far been used for unfettered international navigation, that the concept of an archipelagic State and the corresponding regime was incorporated into UNCLOS 1982.[33]  These deliberations gave rise to the promulgation of “archipelagic sea lanes” and the consequent right of Archipelagic Sea Lane Passage (ASLP) found in Article 53 of UNCLOS.  This article, inter alia, stipulates that “Archipelagic sea lanes passage means the exercise in accordance with this Convention of the rights of navigation and overflight in the normal mode solely for the purpose of continuous, expeditious and unobstructed transit between one part of the high seas or an exclusive economic zone and another part of the high seas or an exclusive economic zone.”[34]

The procedure for promulgation of ASLs begins with the submission of a proposal by the archipelagic state to the IMO — considered to be the “competent international organisation” stated in Article 53 (9) of UNCLOS — following which the IMO assess the conformity of the proposed ASLs with the relevant provisions of UNCLOS.  The IMO may only adopt such ASLs as proposed and jointly agreed by the bordering-State.  Any objection to the proposed ASLs, or the archipelagic State’s failure to designate ASLs would render such sea lanes as non-existent, allowing vessels and aircrafts to traverse through routes designated as those “normally used for international navigation.”[35]

Thus, as a recognised archipelagic State, Indonesia is empowered to designate archipelagic sea lanes (ASL), albeit with due notification to the IMO.[36]  In this regard, through the Maritime Safety Resolution 72(69) and subsequently Government Decree No. 37/2002, also referred to as Alur Laut Kepaulauan Indonesia, Indonesia has promulgated the north/south passages of Sunda-Bangka, Lombok-Makassar, and Ombai-Wetar, as archipelagic sea lanes while the Strait of Malacca and Singapore remains an international strait and not an ASL.[37]   However, the three north/south ASLs are considered by the IMO to be only partially designated, since Indonesia’s proposal did not make mention of the required normal passage routes nor did it designate ASLs along the east/west axis through the Java Sea.[38]  Indonesia has been apprehensive about promulgating east/west ASLs for a number of reasons:

“First, Indonesia did not see a unified proposal from other countries of what the east-west ASL should ideally look like. Instead, it received different ASL proposals from the United States, Great Britain, Japan, and Australia, among others. Second, Indonesia is concerned about the potential security implications of east-west ASLs since they must pass through the Java Sea and would thus expose the heavily populated and economically vital cities on Java’s north to the risks of foreign maritime traffic. For example, a tanker oil spill in the Java Sea could be economically disastrous since the Java Sea provides a significant source of fish and a major location of offshore oil and gas platforms. Finally, the Indonesian government, especially the navy, saw no harm inflicted in the absence of the east west ASL. Even without the east-west ASL, foreign shipping could still make transits under “innocent passage through the archipelagic waters.”[39]

As India develops her maritime capacities and capabilities and assumes greater regional responsibilities within the Indo-Pacific, the importance of understanding, advocating, and executing legally-sustainable passage-regimes through archipelagic States such as Indonesia (and Philippines) cannot be overstated.  In doing so, India and its seagoing agencies (the Indian Navy and the Indian Coast Guard in particular) will need to be respectful of Indonesian (and Filipino) sensitivities.


The foregoing baseline information in respect of international straits contained within the IOR would make it evident that such straits entail two predominant features: geographical position and usage.  Taken together, these would enable India to better extend the requisite degree of stabilising-influence across the region.

Even as New Delhi broadens, deepens, and strengthens its maritime engagement with its partners in the Quad, as also with the several nations with which it has concluded strategic partnerships of one or another hierarchical level, it must not allow itself to be perceived as having acquiesced in the approaches adopted by maritime-powers of the colonial period or, for that matter, those of the WW-II or the Cold War periods.  The perception that India needs to generate and sustain is that of a responsible, mature and reliable partner whose own adherence to the provisions of public international maritime is unequivocal, equitable, and mindful of the imperatives of comity.  This will require the Indian merchant marine, the Coast Guard, and the Indian Navy, as also officials and bureaucrats across a wide swath of governmental ministries, departments and agencies, to comprehend and internalise the legal regimes applicable to international straits, especially those within the Indian Ocean segment of the Indo-Pacific.


About the Authors:

Ms Devika Radha is currently interning at the NMF, within the Foundation’s “Spring 2022” internship programme.  She is in her fifth and final year of an integrated BBA LLB (Hons.) course at the Symbiosis Law School, Pune.  She may be contacted at

Ms Priyasha Dixit, too, is currently interning at the NMF, within the Foundation’s “Spring 2022” internship programme.  She completed her graduate studies from Delhi University and holds a BA degree in Hist and Political Science.  She is now in her final year of a two-year Master of Arts integrated programme majoring in Law, Politics and Society, from the Ambedkar University, New Delhi. She may be contacted at

Ms Zoya Raj Singh, like her fellow co-authors, is currently interning at the NMF, within the Foundation’s “Spring 2022” internship programme.  She completed her graduation from Christ (Deemed) University, Bengaluru, KA and holds a Bachelor of Arts degree in English, Political Science, and History.  She is now pursuing further studies in the OP Jindal Global University, Sonipat, where she is in her final year of a two-year Master of Arts, majoring in International Relations.  She may be contacted at or  


[1] Ensuring Secure Sea: Indian Maritime Security Strategy, Integrated Headquarters, Ministry of Defence (Navy), New Delhi 2015, i-iii.

[2] Caminos Hugo, and Vincent P Cogliati-Bantz, The Legal Regime of Straits: Contemporary Challenges and Solutions, (Cambridge: Cambridge University Press, 2014), 1–8.

[3] Corfu Channel (United Kingdom of Great Britain and Northern Ireland v. Albania), 1949 ICJ, 4.

[4] Mohd Hazmi bin Mohd Rusli, “A Historical Overview on the Legal Status of Straits Used for International Navigation under International Law,” AALCO Journal of International Law 1, No 2 (2014): 103-131,

[5] Oceans Law and Policy Department, Center for Naval Warfare Studies, Annotated Supplement to the Commander’s Handbook on the Law of Naval Operations (Rhode Islands: Naval War College, 1997),  2-14.

[6] Captain Raul (Pete) Pedrozo, “International Straits,” International Law Studies 97, No 39 (2021): 40-43,

[7]  UN General Assembly, Convention on the Law of the Sea, 10 December 1982.

[8] Alexander M Lewis, “International Straits,” International Law Studies 64, No 1 (1991): 5,

[9] Bhavesh Jayanti Lakhani v. State of Maharashtra, (2009) 9 SCC 551.

[10] State of West Bengal v. Kesoram Industries Ltd and Other, (2004) 10 SCC 201.

[11] UNCLOS Article 38

[12] Caminos Hugo, and Vincent P Cogliati-Bantz, The Legal Regime of Straits: Contemporary Challenges and Solutions, (Cambridge: Cambridge University Press, 2014), 37–150. doi:10.1017/CBO9780511777189.027

[13] Moore, The Regime of Straits and the Third United Nations Conference on the Law of the Sea, 74 AM. J. INT’L L. 77, 81-82 (1980)

[14] UNCLOS Article 20

[15] UNCLOS Article 42; Lewis, “International Straits,” 92.

[16] UNCLOS Article 45, cl. 1

[17] UNCLOS Article 25, cl. 3

[18] UNCLOS Article 30.

[19] UNCLOS Article 38-39.

[20] Ministry of Ports, Shipping and Waterways GoI, Maritime India Vision 2030 (New Delhi, 2021), 8.

[21] Frédéric Grare and Mélissa Levaillant, “Getting Real about the Indo-Pacific Redefining European Approach to Maritime Security”, The Hague Centre for Strategic Studies, March 2022.

See also:

Dr Eva Pejsova, “What the European Maritime Initiative in the Strait of Hormuz Tells Us about Brussel’s Security Ambitions”, European Leadership Network,

[22] European Commission, “European Civil Protection and Humanitarian Aid Operations”, Official Website of the European Union,

[23] UNCLOS Chapter XXI.

[24] “Declarations and Reservations,” United Nations Treaty Series, last modified March 13, 2022,

[25] UN General Assembly, Convention on the Territorial Sea and the Contiguous Zone, 29 April 1958,

[26] Bashir Ali Abbas, “The Applicability of International Law of the Sea in the Strait of Hormuz,” Assessing the ‘Law of the Sea’: A Case for the US’ Right of Passage in the Strait of Hormuz, Institute of Peace and Conflict Studies, January 2020.

[27] Nilufer Oral, “Navigating the Oceans: Old and New Challenges for the Law of the Sea for Straits Used for International Navigation,” Ecology Law Quarterly 46, No 163 (2019): 186-187,

[28] Alexander Lott, “Maritime security threats and the passage regime in the Bab-el-Mandeb,” The UNCLOS Blog, 21 June, 2021.

[29] Reuters, “Suez Canal Expansion Due to Finish in July 2023”, 16 January 2022,

[30] “Navigational Regimes of Particular Straits, Sunda and Lombok Case Study,” International Institute for Law of the Sea Studies, last modified April 24, 2021,

[31] Gurpreet Khurana, “The Malacca Strait “Conundrum” and India”, in Changing Security Dynamics in Southeast Asia, eds NS Sisodia, (New Delhi: Institute for Defence Studies and Analyses, 2008), 126.

[32] Sujan R Chinoy, “Time to Leverage the Strategic Potential of Andaman & Nicobar Islands,” Manohar-Parrikar Institute for Defence Studies and Analyses,

[33] Erik Franckx and Aster Boeye, Archipelagic States, (New York: Oxford University Press, 2020).

[34] UNCLOS Article 53.3

[35] Masitha Tismanana Kumala and Dina Sunyowati, “Designation of Archipelagic Sea Lanes According to the Convention on the Law of the Sea 1982 (Indonesia Archipelagic Sea Lanes Case),” International Journal of Business, Economic and Law 10, No 4 (2016): 50,

[36] UNCLOS article 53.1

[37] Vivien Jane Evangelio Cay, “Archipelagic Sea Lanes Passage and Maritime Security in Archipelagic Southeast Asia” (MA dissertation, World Maritime University, Sweden, 2010), 44-46.

[38] Dhiana Puspitawati, “The East/West Archipelagic Sea Lanes Passage through the Indonesian Archipelago,” Maritime Studies 140 (2014): 1-13,

[39] Ristian Atriandi Supriyanto, “Developing Indonesia’s Maritime Strategy Under President Jokowi,” The Asan Forum (2016): 8-9.


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