Summary 4

1 The shadow fleet 7

1.1 Background: Sanctioning Russian oil 7

1.2 Targeting Russia’s shadow fleet 10

2 UK plan to enforce sanctions against the shadow fleet 14

2.1 Government announces plan to interdict shadow fleet 14

2.2 January 2026 seizure operation with the US 15

2.3 First operation to intercept the shadow fleet by UK forces, 14 June 2026 16

2.4 UK references to legal basis 17

2.5 Russia’s response 19

3 The UK sanctions framework and shipping sanctions 20

3.1 Sanctions powers relating to ships 20

3.2 Maritime enforcement 21

4 The law of the sea 24

4.1 Maritime zones 24

4.2 Flag states 26

4.3 Freedom of navigation 26

4.4 Treating shadow fleet vessels as ‘stateless’ 28

4.5 Legal issues in UK waters 33

5 Further Reading and Commentary 41