2.1 The Legal Concept of a Strait
The meaning of the terms “strait” and “strait used for international navigation” (hereafter as a euphemism “international strait”) are left undefined in the 1982 United Nations Convention on the Law of the Sea1 (hereafter losc or Convention). Under the present author’s interpretation of losc, an international strait is a natural sea passage that is used for international navigation between two larger maritime areas, and which is not more than 24 nautical miles (hereafter nm) wide as measured from coast to coast or from baseline to baseline and, in respect of which, international navigation is safeguarded under the Convention. In Europe alone, over 30 natural sea passages meet the criteria of an international strait (see Map 1).
European Straits
source: base map is created by marineregions.org, ‘europe’, flanders marine institute (vliz), 2010, available
The 24-nm-limit follows from the teleological interpretation of Part iii of the losc that was designed to safeguard passage rights in and above straits in the context of the extension of the maximum outer limit of territorial sea to 12 nm. This means that straits which include an eez or the high seas corridor (so-called Article 36-category of straits) still meet the legal definition of strait provided that they are up to 24 nm wide. This follows from Article 35(b) of losc which stipulates that nothing in Part iii of the Convention affects the legal status of the waters beyond the territorial seas of States bordering straits as eezs or high seas.
Hence, the eez or high seas corridor in the Article 36-type of international strait could be established by strait States by means of voluntarily limiting the width of the outer limits of their territorial sea. As examined below, this method has been used by Japan in respect of many straits that would be otherwise located entirely in its territorial sea or internal waters and by the Baltic strait States in respect of, inter alia, the Kadet and Femer straits,2 Bornholmsgat3
In addition, there are cases where the legal regime of a strait is applicable to a strait only in a small part of a strait’s geographical limits, e.g., the Strait of Malacca,9 or Part iii of losc has extended the spatial limits of a strait as compared to its commonly accepted geographical borders, e.g., the Bab el-Mandeb.10 These examples show that law is redefining our long-held (geographic) understandings of what constitutes a strait.
2.2 The Legal Classification of Straits
losc recognises various navigational regimes, including the freedom of navigation and overflight, transit passage, archipelagic sea lanes passage, suspendable and non-suspendable innocent passage, special passage regimes, and passage subject to the coastal State’s authorisation. Nearly half of them are
There are six types of international straits: (1) geographic straits through which a high-seas corridor exists (such as the Taiwan Strait or some of the Japanese straits); (2) straits governed by long-standing conventions (such as the afore-mentioned Strait of Magellan and the Turkish Straits, as well as the Danish Straits); (3) straits with routes through the high seas or eez that are of similar convenience; (4) straits formed by islands (e.g., the Messina Strait); (5) archipelagic straits governed by archipelagic sea lanes passage, and (6) dead end straits. Each archetype has unique characteristics.11
Under the present author’s interpretation of the Convention, it is possible to distinguish also numerous other legal categories of straits, some of which are based on a provision of losc that falls outside Part iii of the Convention that is specifically devoted to the legal regime of straits. Based on a systemic interpretation of the Convention, the legal categories of straits and the corresponding navigational regimes are systemized in the table below (see Table 1).
Legal categories of Straitsa
Legal basis |
Category of straits |
Passage regime |
Examples |
|---|---|---|---|
International straits |
|||
Art 37 losc |
Strait linking two parts of an eez or the high seas |
Transit passage |
The straits of Dover, Gibraltar, Malacca, Hormuz, Bab el-Mandeb |
Art 38(1) losc |
Strait formed by an island of a strait State and its mainland coast |
Non-suspendable innocent passage |
The Strait of Messina Kalmarsund Corfu Channel |
Art 45(1)(b) losc |
Strait linking eez/high seas with a foreign State’s territorial sea |
Non-suspendable innocent passage |
The Strait of Tiran (prior to the 1979 Treaty) Head Harbour Passage |
Art 53 losc |
Strait in the archipelagic waters |
Archipelagic Sea Lanes Passage |
Sunda Strait Lombok Strait Makassar Strait |
Art 36 losc |
Strait that includes an eez or the high seas corridor |
Freedom of Navigation & Overflight |
Femer Belt, Kadet, Viro Strait (Gulf of Finland), Tsugaru, Osumi, Soya, Bornholmsgat |
Art 311(2) losc |
Sui generis strait |
Specific passage regime |
The Strait of Tiran (1979 Treaty) The Kerch Strait (2003 Treaty) The Baltiysk Strait (2009 Treaty) |
Art 35(c) losc |
Strait regulated by a long-standing international convention |
Specific passage regime |
The Danish Straits The Åland Strait The Strait of Magellan The Turkish Straits |
Art 234 losc |
Potentially/contested: ice-covered strait |
Specific passage regime |
The Northwest Passage The Northern Sea Route |
Non-international straits |
|||
Art 35(a) losc |
Strait in long-standing internal waters |
Permit-based passage |
The Sea of Straits The Archipelago Sea straits |
Non-navigable strait |
Presence of barriers, e.g., causeways |
The Canso Strait The Johor Strait Väike väin (the Small Strait) |
|
This book centres around the above-listed legal categories of straits when examining the legality of navigational restrictions in hybrid conflicts and hybrid warfare. In this context, particular emphasis lies on studying such complex situations where navigation through a strait is governed by parallel passage regimes. This occurs where the strait States or the strait State and user States disagree on the passage regime that applies to a particular strait. It results in a ‘grey area’ in relation to the governance of a strait, since strait State(s) and user States are unwilling to agree on a uniform set of rules for the regulation of passage of foreign ships and aircraft in and above the relevant strait.
Parallel legal regimes of a strait may be caused, e.g., by a user State’s note of diplomatic protest to the strait State’s domestic legal act that regulates passage in a particular strait (e.g., the United States objections to the Russian Federation’s domestic regulations on the Northern Sea Route). A strait may be subject to different regimes also because of another State’s objection to State continuity (e.g., the Estonian Straits) or the non-recognition of an unlawful territorial annexation (e.g., the Kerch Strait). Furthermore, the legal regime of the Strait of Hormuz illustrates that a parallel legal regime of a strait may be the consequence of partial non-applicability of losc to the regulation of navigation in a strait due to, e.g., the strait State’s objection to the regime of transit passage as well as its or user State’s decision to abstain from becoming a party to the losc (see infra Chapter 8.4 of Part 3).
The parallel legal regimes may result in situations where parties to a dispute may be in diametrically opposing positions over whether international navigation through a particular strait is regulated by the right of transit passage, non-suspendable innocent passage, specific treaty regime or permit-based passage. This results in legal uncertainty over passage rights which, in turn, is a fertile ground for the escalation of hybrid conflicts. Such disputes often lead to actual maritime incidents and conflicts between the parties as illustrated by the naval incidents in the Kerch Strait and the Strait of Hormuz. Ukraine claims that passage through the Kerch Strait is regulated by the regime of transit passage, whereas the Russian Federation considers that the Kerch Strait is subject to a specific treaty regime. Similarly, the United States considers that the regime of transit passage applies to its ships and aircraft in and over the Strait of Hormuz, while Iran recognises the applicability of the right of innocent passage.
2.3 The Law of Naval Warfare in Straits and Its Relation to the Law of the Sea
losc does not regulate matters of war. Instead, pursuant to the meaning of its preamble, naval warfare is regulated by the rules and principles of general international law. Yet this does not mean that losc loses its significance in an armed conflict. The legal framework and the rules stipulated in the losc in respect of various maritime zones and activities therein largely continue to apply in times of war, both in respect of neutral as well as belligerent States.12 Furthermore, as argued by Heintschel von Heinegg, the violation by a foreign warship of the rules of (non-suspendable) innocent passage or transit passage in straits and by not complying with the coastal State’s order to leave its territorial sea might potentially per se amount to the use of force under Article 2(4) of the United Nations (hereafter UN) Charter that triggers the applicability of jus in bello.13
Straits gain an increased significance in an armed conflict as the control over these vital sea lanes is of strategic importance for the belligerent war efforts. At the same time, navigation through straits in times of war is threatened not only from the presence of belligerent warships patrolling these narrow waterways, but also from attacks launched from adjacent coasts and
The rules of customary international law applicable to naval warfare in international straits is largely reflected in Section ii of the San Remo Manual. According to the San Remo Manual, ships and aircraft retain in an armed conflict their rights of transit and archipelagic sea lanes passage through, under or over neutral international straits, but, at the same time, transiting ships must not jeopardize the neutrality of the strait State.15 Furthermore, belligerent ships, submarines and aircraft have the rights of transit passage and archipelagic sea lanes passage also in non-neutral straits (‘through, under, and over all straits’) to which these rights generally apply.16 Yet they can be subject to belligerent attacks while navigating in or over such straits.17 Caminos and Cogliati-Bantz note that: “It is beyond doubt that a belligerent State bordering a strait is not obliged to respect the right of transit of enemy vessels.”18 By contrast, ships and aircraft of neutral States retain their passage rights and cannot be attacked while transiting belligerent straits.19
The foregoing also applies to the right of non-suspendable innocent passage in international straits in an armed conflict.20 Unlike the coastal State’s general right to temporarily suspend innocent passage through its territorial sea on, e.g., security grounds, the right of innocent passage through international straits cannot be suspended under customary international law. This was recognised by the International Court of Justice (hereafter icj) in the
In the Corfu Channel incident, the warships of the United Kingdom struck Albanian mines while navigating the Corfu Channel. The icj noted that at the time Greece considered herself as being ‘technically’ in an armed conflict with Albania, and that Albania, “in view of these exceptional circumstances, would have been justified in issuing regulations in respect of the passage of warships [of neutral States] through the Strait, but not in prohibiting such passage or in subjecting it to the requirement of special authorization.”22 Consequently, the Court upheld the right of non-suspendable innocent passage through an international strait that cannot be denied for neutral shipping even in times of war.
By now, similar conclusions can be drawn in respect of the right of transit passage. Heintschel von Heinegg maintains that: “Recent state practice also indicates the existence of a rule prohibiting the suspension of the right of transit passage, even during an international armed conflict.”23 Similar to the San Remo Manual, he finds that the right of transit passage and non-suspendable innocent passage cannot be denied by belligerents in respect of neutral States.24
The extent of the right of innocent passage of warships was at the time of the Corfu Channel case still unclear, particularly in the context of an international armed conflict between the strait State and another State. Equally, it was disputed whether the Corfu Channel constitutes such narrow sea passage through which international navigation needs to be safeguarded under international law. Albania maintained in the Corfu Channel case that by sending its warships through the Albanian territorial sea in the Corfu Channel, the United Kingdom violated its sovereignty and that Albania was entitled, in such exceptional circumstances, to regulate the passage of foreign warships through its territorial sea by requiring that foreign warships apply for a prior authorisation.25 Albania also alleged that the passage of the Royal Navy’s warships through its territorial sea was not of an innocent character.26 The icj rejected the Albanian claims.27
However, there are, arguably, exceptions to this rule. First, as noted by Heintschel von Heinegg as well as Caminos and Cogliati-Bantz, a strait State might be entitled to close the airspace for overflight of neutral aircraft, let alone belligerent aircraft, in an armed conflict due to its security considerations.31 Furthermore, as Caminos and Cogliati-Bantz point out, it is open to interpretation whether the strait State is entitled to completely close an international strait subject to military necessity and if ‘justified by the gravest of circumstances’.32 Similarly, for Heintschel von Heinegg this question ‘is a matter of dispute’.33
United Nations Convention on the Law of the Sea, adopted 10 December 1982, entered into force 16 November 1994, 1833 unts 397.
Section 1 of the Proclamation by the Government of the Federal Republic of Germany concerning the extension of the breadth of the German territorial sea, adopted 11 November 1994, entered into force 1 January 1995, available
Exchange of Notes Constituting an Agreement between Denmark and Sweden concerning the Delimitation of the Territorial Waters between Denmark and Sweden, adopted 25 June 1979, entered into force 21 December 1979, available
Exchange of Notes Constituting an Agreement on the Procedure to be followed in the Modification of the Limits of the Territorial Waters in the Gulf of Finland, adopted 4 May 1994, entered into force 31 July 1995, 1887 unts 223.
E.g., the western part of the Strait of Hormuz in the Persian Gulf, see infra Chapter 8.2 of Part 3.
Infra Chapter 14 of Part 4.
Infra Chapter 9 of Part 3.
Infra Chapter 14 of Part 4.
Infra Chapter 6.1 of Part 2.
J Kraska, R Pedrozo, International Maritime Security Law (Martinus Nijhoff, Leiden/ Boston, 2013), 224.
See Kraska and Pedrozo, op. cit., 864. N Klein, Maritime Security and the Law of the Sea (Oxford University Press, Oxford 2013), 259. W Heintschel von Heinegg, ‘The Law of Armed Conflict at Sea’, in D Fleck (ed.), The Handbook of International Humanitarian Law (2nd Ed, Oxford University Press, Oxford, 2009), 476ff. H Caminos, VP Cogliati-Bantz, The Legal Regime of Straits: Contemporary Challenges and Solutions (Cambridge University Press, Cambridge, 2014), 11–12.
W Heintschel von Heinegg, ‘The difficulties of conflict classification at sea: Distinguishing incidents at sea from hostilities’, (2016) 98(2) International Review of the Red Cross, 457–459.
See M Õun, Juminda miinilahing 1941 – maailmasündmus meie koduvetes (Juminda Sentinel, Juminda, 2006).
San Remo Manual on International Law Applicable to Armed Conflicts at Sea, 12 June 1994, Rules 23–25, 27. Available:
Ibid., Rules 27–28.
W Heintschel von Heinegg, ‘The Law of Naval Warfare and International Straits’ (1998) 71 International Law Studies, 265.
Caminos and Cogliati-Bantz, op. cit., 21.
San Remo Manual, op. cit., Rule 26.
Ibid., Rule 33.
Corfu Channel Case (United Kingdom v. Albania), Judgment, i.c.j. Reports 1949, 28.
The Corfu Channel Case, op. cit., 29.
Heintschel von Heinegg 1998, op. cit., 265.
Ibid., 266.
The Corfu Channel Case, op. cit., 12.
Ibid.
Ibid., 29.
Caminos and Cogliati-Bantz, op. cit., 27.
San Remo Manual, op. cit., Rule 89.
Caminos and Cogliati-Bantz, op. cit., 25–27.
Heintschel von Heinegg 1998, op. cit., 267, 270. Caminos and Cogliati-Bantz, op. cit., 29.
Caminos and Cogliati-Bantz, op. cit., 30.
Heintschel von Heinegg 1998, op. cit., 265. Based on a detailed examination of the applicable law and State practice in the 20th century, the author notes that ‘it is far from clear’ in which cases the right of transit passage may be restricted in respect of neutral shipping. Ibid., 266.