Alexander Lott, Ph.D. (2017), is Marie Curie fellow at the Norwegian Centre for the Law of the Sea, University of Tromsø and affiliated to the University of Tartu. He has published monographs and many articles on maritime law and security.

• PrefaceAcknowledgementsList of IllustrationsAbbreviations and Euphemismspart 1The Meaning of Straits and Hybrid Threats1 The Implications of Hybrid Threats to the Maritime Domain2 The Legal Concept and Classification of Straits2.1 The Legal Concept of a Strait2.2 The Legal Classification of Straits2.3 The Law of Naval Warfare in Straits and Its Relation to the Law of the Sea3 The Concept of Hybrid Threats3.1 The Meaning of Hybrid Conflicts3.2 Differences between the Rules on the Use of Force in Maritime Law Enforcement Operations and Armed Conflicts3.3 The Meaning of Hybrid Warfarepart 2Use of Force in Maritime Hybrid Warfare4 Permit-Based Passage v. Transit Passage in an Occupied Area The 2018 Kerch Strait Incident and the 2022 Ukraine-Russia Naval Warfare4.1 The Kerch Strait Incident and Its Implications for the Passage Regime in the Sea of Azov4.2 Freedom of Navigation of Ukrainian and Russian Ships in the Kerch Strait4.3 A Critical Analysis of Ukraine’s Arguments about the Applicability of Transit Passage to Ships and Aircraft in/over the Sea of Azov and the Kerch Strait4.4 The Significance of 2003 Bilateral Treaties for the Passage Regime of the Kerch Strait4.5 The Sea of Azov as a Potential Historic Bay and Its Implications for the Regime of Passage in the Kerch Strait under Article 35(a) of losc4.6 The Importance of the Obligation of Non-recognition for the Passage Regime of the Kerch Strait4.7 Parallel Legal Regimes vs Sui Generis Regime of the Kerch Strait4.8 The Kerch Strait as a Belligerent Strait5 Use of Force against Sovereign Immune Vessels Law Enforcement v. Humanitarian Law Paradigm5.1 In dubio pro jus in bello?5.2 Threshold of an Armed Attack in a Hybrid Naval Conflict5.3 Distinction between Law Enforcement and Humanitarian Law Paradigms6 Iran-Israel ‘Shadow War’ in Waters around the Arabian Peninsula and Incidents near the Bab el-Mandeb6.1 Legal Regime of the Bab el-Mandeb6.2 Geopolitical Characteristics of the Bab el-Mandeb6.3 Terrorism and Piracy in and near the Bab el-Mandeb6.4 Armed Conflict in Yemen6.5 Background of the Iran-Israel Conflict6.6 Problems with Attributing State Responsibility6.7 Non-state Actors and Article 51 of the UN Charter7 Russia’s Military Operations in the Territories of the Viro Strait’s Coastal States7.1 Geographical and Geopolitical Characteristics of the Viro Strait7.2 The Legal Regime of the Viro Strait7.3 Foreign Military Activities in the Viro Strait: Incursions of Foreign Submarines and Military Aircraftpart 3Discriminatory Navigational Restrictions in Hybrid Conflicts8 Discriminatory Prohibition of the Right of Transit Passage of a Commercial Ship The Arrest of Stena Impero by Iran8.1 Geographical and Geopolitical Characteristics of the Strait of Hormuz8.2 Legal Regime of the Strait of Hormuz8.3 The 2019 Stena Impero Incident and the Traffic Separation Scheme in the Strait of Hormuz8.4 Parallel Passage Regimes in the Strait of Hormuz?8.5 Significance of Iranian Internal Waters for the Passage Regime in the Strait of Hormuz9 Tensions in and over the Taiwan Strait in 20219.1 Legal and Geographical Characteristics of the Taiwan Strait9.2 Navigation in the Taiwan Strait in the Light of Recent Developments in China’s Legislation9.3 Geopolitical Tensions in the Taiwan Strait and Intrusions of Taiwan’s Air Defence Identification Zone10 Discriminatory Navigational Restrictions in the Kerch Strait in Respect of Foreign Commercial Ships10.1 The Significance of the Kerch Strait for Commerce10.2 Restrictions on Foreign Commercial Ships’ Navigation through the Kerch Strait11 Discriminatory Prohibition of the Right of Innocent Passage of a Commercial Ship The Vironia Incident in the Gulf of Finland11.1 Right of Innocent Passage in the Eastern Gulf of Finland from 1920s to 200011.2 The Russian Federation’s Maritime Zones in the Gulf of Finland11.3 The Vironia Incident in the Gulf of Finland and Its Aftermath11.4 Potential Legal Basis of the Russian Federation’s Permit-Based Passage Regime in the Gulf of Finlandpart 4Major Maritime Industrial Projects, Piracy, and Unidentified Soldiers12 The Nord Stream Project and Estonian-Russian Incidents in the Viro Strait12.1 Link between Industrial Projects and Maritime Security12.2 The Significance of the Viro Strait’s eez Corridor for the Nord Stream Project12.3 Marine Scientific Research in the Context of Seabed Studies on the Pipeline Route12.4 The Incident between the Estonian Coast Guard and Russian Research Vessels in the Viro Strait’s eez Corridor12.5 Permit-Based Marine Scientific Research in an eez: Estonia’s Decision to Deny Seabed Surveys13 Countering the Threat of ‘Little Green Men’ in the Åland Strait13.1 Geopolitical Characteristics of the Åland Strait and Preparations to Counter Unidentified Soldiers on the Åland Islands13.2 Legal Regime of the Åland Strait14 Threats of Piracy in the Straits of Malacca, Sunda, Lombok14.1 Legal and Geopolitical Characteristics14.2 Threats of Piracy in Indonesia and the Straits of Malacca and Singaporepart 5Concluding Observations on the Implications of Hybrid Threats for Maritime Security Law15 A Need for a New Legal Framework on Hybrid Naval Warfare?16 Discriminatory Navigational Restrictions in the Context of Hybrid Conflicts17 Low-Intensity Use of Force (Hybrid Warfare) through the Prism of Law Enforcement and an Armed Attack18 Guidelines for Distinguishing between the Rules of Armed Conflict and Law Enforcement in Grey Zone Naval Incidents18.1 Use of Force by State Vessels against Attacks Launched from Commercial Ships18.2 Use of Force against a Commercial Ship in a Law Enforcement Operation18.3 State vs State ScenarioBibliographyChronological Table of International InstrumentsTable of National LegislationChronological Table of CasesChronological List of MapsIndex

Alexander Lott, Ph.D. (2017), is Marie Curie fellow at the Norwegian Centre for the Law of the Sea, University of Tromsø and affiliated to the University of Tartu. He has published monographs and many articles on maritime law and security.

• PrefaceAcknowledgementsList of IllustrationsAbbreviations and Euphemismspart 1The Meaning of Straits and Hybrid Threats1 The Implications of Hybrid Threats to the Maritime Domain2 The Legal Concept and Classification of Straits2.1 The Legal Concept of a Strait2.2 The Legal Classification of Straits2.3 The Law of Naval Warfare in Straits and Its Relation to the Law of the Sea3 The Concept of Hybrid Threats3.1 The Meaning of Hybrid Conflicts3.2 Differences between the Rules on the Use of Force in Maritime Law Enforcement Operations and Armed Conflicts3.3 The Meaning of Hybrid Warfarepart 2Use of Force in Maritime Hybrid Warfare4 Permit-Based Passage v. Transit Passage in an Occupied Area The 2018 Kerch Strait Incident and the 2022 Ukraine-Russia Naval Warfare4.1 The Kerch Strait Incident and Its Implications for the Passage Regime in the Sea of Azov4.2 Freedom of Navigation of Ukrainian and Russian Ships in the Kerch Strait4.3 A Critical Analysis of Ukraine’s Arguments about the Applicability of Transit Passage to Ships and Aircraft in/over the Sea of Azov and the Kerch Strait4.4 The Significance of 2003 Bilateral Treaties for the Passage Regime of the Kerch Strait4.5 The Sea of Azov as a Potential Historic Bay and Its Implications for the Regime of Passage in the Kerch Strait under Article 35(a) of losc4.6 The Importance of the Obligation of Non-recognition for the Passage Regime of the Kerch Strait4.7 Parallel Legal Regimes vs Sui Generis Regime of the Kerch Strait4.8 The Kerch Strait as a Belligerent Strait5 Use of Force against Sovereign Immune Vessels Law Enforcement v. Humanitarian Law Paradigm5.1 In dubio pro jus in bello?5.2 Threshold of an Armed Attack in a Hybrid Naval Conflict5.3 Distinction between Law Enforcement and Humanitarian Law Paradigms6 Iran-Israel ‘Shadow War’ in Waters around the Arabian Peninsula and Incidents near the Bab el-Mandeb6.1 Legal Regime of the Bab el-Mandeb6.2 Geopolitical Characteristics of the Bab el-Mandeb6.3 Terrorism and Piracy in and near the Bab el-Mandeb6.4 Armed Conflict in Yemen6.5 Background of the Iran-Israel Conflict6.6 Problems with Attributing State Responsibility6.7 Non-state Actors and Article 51 of the UN Charter7 Russia’s Military Operations in the Territories of the Viro Strait’s Coastal States7.1 Geographical and Geopolitical Characteristics of the Viro Strait7.2 The Legal Regime of the Viro Strait7.3 Foreign Military Activities in the Viro Strait: Incursions of Foreign Submarines and Military Aircraftpart 3Discriminatory Navigational Restrictions in Hybrid Conflicts8 Discriminatory Prohibition of the Right of Transit Passage of a Commercial Ship The Arrest of Stena Impero by Iran8.1 Geographical and Geopolitical Characteristics of the Strait of Hormuz8.2 Legal Regime of the Strait of Hormuz8.3 The 2019 Stena Impero Incident and the Traffic Separation Scheme in the Strait of Hormuz8.4 Parallel Passage Regimes in the Strait of Hormuz?8.5 Significance of Iranian Internal Waters for the Passage Regime in the Strait of Hormuz9 Tensions in and over the Taiwan Strait in 20219.1 Legal and Geographical Characteristics of the Taiwan Strait9.2 Navigation in the Taiwan Strait in the Light of Recent Developments in China’s Legislation9.3 Geopolitical Tensions in the Taiwan Strait and Intrusions of Taiwan’s Air Defence Identification Zone10 Discriminatory Navigational Restrictions in the Kerch Strait in Respect of Foreign Commercial Ships10.1 The Significance of the Kerch Strait for Commerce10.2 Restrictions on Foreign Commercial Ships’ Navigation through the Kerch Strait11 Discriminatory Prohibition of the Right of Innocent Passage of a Commercial Ship The Vironia Incident in the Gulf of Finland11.1 Right of Innocent Passage in the Eastern Gulf of Finland from 1920s to 200011.2 The Russian Federation’s Maritime Zones in the Gulf of Finland11.3 The Vironia Incident in the Gulf of Finland and Its Aftermath11.4 Potential Legal Basis of the Russian Federation’s Permit-Based Passage Regime in the Gulf of Finlandpart 4Major Maritime Industrial Projects, Piracy, and Unidentified Soldiers12 The Nord Stream Project and Estonian-Russian Incidents in the Viro Strait12.1 Link between Industrial Projects and Maritime Security12.2 The Significance of the Viro Strait’s eez Corridor for the Nord Stream Project12.3 Marine Scientific Research in the Context of Seabed Studies on the Pipeline Route12.4 The Incident between the Estonian Coast Guard and Russian Research Vessels in the Viro Strait’s eez Corridor12.5 Permit-Based Marine Scientific Research in an eez: Estonia’s Decision to Deny Seabed Surveys13 Countering the Threat of ‘Little Green Men’ in the Åland Strait13.1 Geopolitical Characteristics of the Åland Strait and Preparations to Counter Unidentified Soldiers on the Åland Islands13.2 Legal Regime of the Åland Strait14 Threats of Piracy in the Straits of Malacca, Sunda, Lombok14.1 Legal and Geopolitical Characteristics14.2 Threats of Piracy in Indonesia and the Straits of Malacca and Singaporepart 5Concluding Observations on the Implications of Hybrid Threats for Maritime Security Law15 A Need for a New Legal Framework on Hybrid Naval Warfare?16 Discriminatory Navigational Restrictions in the Context of Hybrid Conflicts17 Low-Intensity Use of Force (Hybrid Warfare) through the Prism of Law Enforcement and an Armed Attack18 Guidelines for Distinguishing between the Rules of Armed Conflict and Law Enforcement in Grey Zone Naval Incidents18.1 Use of Force by State Vessels against Attacks Launched from Commercial Ships18.2 Use of Force against a Commercial Ship in a Law Enforcement Operation18.3 State vs State ScenarioBibliographyChronological Table of International InstrumentsTable of National LegislationChronological Table of CasesChronological List of MapsIndex

Alexander Lott, Ph.D. (2017), is Marie Curie fellow at the Norwegian Centre for the Law of the Sea, University of Tromsø and affiliated to the University of Tartu. He has published monographs and many articles on maritime law and security.

• PrefaceAcknowledgementsList of IllustrationsAbbreviations and Euphemismspart 1The Meaning of Straits and Hybrid Threats1 The Implications of Hybrid Threats to the Maritime Domain2 The Legal Concept and Classification of Straits2.1 The Legal Concept of a Strait2.2 The Legal Classification of Straits2.3 The Law of Naval Warfare in Straits and Its Relation to the Law of the Sea3 The Concept of Hybrid Threats3.1 The Meaning of Hybrid Conflicts3.2 Differences between the Rules on the Use of Force in Maritime Law Enforcement Operations and Armed Conflicts3.3 The Meaning of Hybrid Warfarepart 2Use of Force in Maritime Hybrid Warfare4 Permit-Based Passage v. Transit Passage in an Occupied Area The 2018 Kerch Strait Incident and the 2022 Ukraine-Russia Naval Warfare4.1 The Kerch Strait Incident and Its Implications for the Passage Regime in the Sea of Azov4.2 Freedom of Navigation of Ukrainian and Russian Ships in the Kerch Strait4.3 A Critical Analysis of Ukraine’s Arguments about the Applicability of Transit Passage to Ships and Aircraft in/over the Sea of Azov and the Kerch Strait4.4 The Significance of 2003 Bilateral Treaties for the Passage Regime of the Kerch Strait4.5 The Sea of Azov as a Potential Historic Bay and Its Implications for the Regime of Passage in the Kerch Strait under Article 35(a) of losc4.6 The Importance of the Obligation of Non-recognition for the Passage Regime of the Kerch Strait4.7 Parallel Legal Regimes vs Sui Generis Regime of the Kerch Strait4.8 The Kerch Strait as a Belligerent Strait5 Use of Force against Sovereign Immune Vessels Law Enforcement v. Humanitarian Law Paradigm5.1 In dubio pro jus in bello?5.2 Threshold of an Armed Attack in a Hybrid Naval Conflict5.3 Distinction between Law Enforcement and Humanitarian Law Paradigms6 Iran-Israel ‘Shadow War’ in Waters around the Arabian Peninsula and Incidents near the Bab el-Mandeb6.1 Legal Regime of the Bab el-Mandeb6.2 Geopolitical Characteristics of the Bab el-Mandeb6.3 Terrorism and Piracy in and near the Bab el-Mandeb6.4 Armed Conflict in Yemen6.5 Background of the Iran-Israel Conflict6.6 Problems with Attributing State Responsibility6.7 Non-state Actors and Article 51 of the UN Charter7 Russia’s Military Operations in the Territories of the Viro Strait’s Coastal States7.1 Geographical and Geopolitical Characteristics of the Viro Strait7.2 The Legal Regime of the Viro Strait7.3 Foreign Military Activities in the Viro Strait: Incursions of Foreign Submarines and Military Aircraftpart 3Discriminatory Navigational Restrictions in Hybrid Conflicts8 Discriminatory Prohibition of the Right of Transit Passage of a Commercial Ship The Arrest of Stena Impero by Iran8.1 Geographical and Geopolitical Characteristics of the Strait of Hormuz8.2 Legal Regime of the Strait of Hormuz8.3 The 2019 Stena Impero Incident and the Traffic Separation Scheme in the Strait of Hormuz8.4 Parallel Passage Regimes in the Strait of Hormuz?8.5 Significance of Iranian Internal Waters for the Passage Regime in the Strait of Hormuz9 Tensions in and over the Taiwan Strait in 20219.1 Legal and Geographical Characteristics of the Taiwan Strait9.2 Navigation in the Taiwan Strait in the Light of Recent Developments in China’s Legislation9.3 Geopolitical Tensions in the Taiwan Strait and Intrusions of Taiwan’s Air Defence Identification Zone10 Discriminatory Navigational Restrictions in the Kerch Strait in Respect of Foreign Commercial Ships10.1 The Significance of the Kerch Strait for Commerce10.2 Restrictions on Foreign Commercial Ships’ Navigation through the Kerch Strait11 Discriminatory Prohibition of the Right of Innocent Passage of a Commercial Ship The Vironia Incident in the Gulf of Finland11.1 Right of Innocent Passage in the Eastern Gulf of Finland from 1920s to 200011.2 The Russian Federation’s Maritime Zones in the Gulf of Finland11.3 The Vironia Incident in the Gulf of Finland and Its Aftermath11.4 Potential Legal Basis of the Russian Federation’s Permit-Based Passage Regime in the Gulf of Finlandpart 4Major Maritime Industrial Projects, Piracy, and Unidentified Soldiers12 The Nord Stream Project and Estonian-Russian Incidents in the Viro Strait12.1 Link between Industrial Projects and Maritime Security12.2 The Significance of the Viro Strait’s eez Corridor for the Nord Stream Project12.3 Marine Scientific Research in the Context of Seabed Studies on the Pipeline Route12.4 The Incident between the Estonian Coast Guard and Russian Research Vessels in the Viro Strait’s eez Corridor12.5 Permit-Based Marine Scientific Research in an eez: Estonia’s Decision to Deny Seabed Surveys13 Countering the Threat of ‘Little Green Men’ in the Åland Strait13.1 Geopolitical Characteristics of the Åland Strait and Preparations to Counter Unidentified Soldiers on the Åland Islands13.2 Legal Regime of the Åland Strait14 Threats of Piracy in the Straits of Malacca, Sunda, Lombok14.1 Legal and Geopolitical Characteristics14.2 Threats of Piracy in Indonesia and the Straits of Malacca and Singaporepart 5Concluding Observations on the Implications of Hybrid Threats for Maritime Security Law15 A Need for a New Legal Framework on Hybrid Naval Warfare?16 Discriminatory Navigational Restrictions in the Context of Hybrid Conflicts17 Low-Intensity Use of Force (Hybrid Warfare) through the Prism of Law Enforcement and an Armed Attack18 Guidelines for Distinguishing between the Rules of Armed Conflict and Law Enforcement in Grey Zone Naval Incidents18.1 Use of Force by State Vessels against Attacks Launched from Commercial Ships18.2 Use of Force against a Commercial Ship in a Law Enforcement Operation18.3 State vs State ScenarioBibliographyChronological Table of International InstrumentsTable of National LegislationChronological Table of CasesChronological List of MapsIndex