The War at Sea: Is There a Naval Blockade in the Sea of Azov?

Although land operations have garnered most attention, the war between Ukraine and the Russian Federation also rages at and from the sea. During these last weeks, several merchant vessels were attacked and seized, some apparently within the territorial sea of a NATO Member State. Naval mines have been spotted, amphibious operations undertaken, naval fires used on objectives on land, and in the weeks leading up to the war much mention was made of Russia effectively blockading the Sea of Azov. Talks of blockade have since continued, also within the context of the need to find safe corridors for civilians and seafarers to escape the war. But is there really a naval blockade in the Sea of Azov?

 Naval Blockade

Undoubtedly, the law of naval warfare applies to this international armed conflict. This specialized section of the law of armed conflict includes the law of blockade. Apart from one rule in the Paris Declaration, drafted after the end of the Crimean War of 1853-1856, the law of naval blockade remains uncodified under customary international law.

It is widely accepted that a blockade, to be legally established, requires notification and enforcement in an effective and impartial manner. The purpose of a blockade is to stop all ingress and egress of vessels of all States from an enemy coast or port. The legal point to note is that once a blockade is legally established, it creates belligerent rights against other users of the sea, such as the seizure and capture of vessels irrespective of their flag. Also, vessels attempting to breach a blockade become liable to attack by the blockading force. Considering the requirements of notification, effectiveness, and impartiality, what then is the situation in the Sea of Azov?

Situation

 On 24 February, Russia announced suspension of commercial traffic in the Sea of Azov. Since the war broke out, commercial vessels and their crews have been stranded in Ukrainian ports, unable to sail. It has been speculated that Russian warships will fire at any vessel that moves in the area and that ships are locked in ports because the surrounding waters are mined, making navigation unsafe.

Logistical challenges have also been raised to the International Maritime Organization (IMO), which reported that “Ukraine closed its seaports effectively trapping merchant ships without the services such as tugs and harbor pilots to depart and straining the ability to re-provision the ships.” The Ukraine government sent a letter to the IMO a day after the war broke out indicating that all Ukrainian ports are closed for entry and exit. Others have observed that “[s]ome 140 cargo ships are stuck at Ukraine’s now-closed ports, unable to leave because traveling through the Black Sea involves extreme risk.”

This dire situation, in which vessels and their crews appear to be blocked for several reasons, does not, however, mean a naval blockade actually has been established.

Notification

Apart from the suspension of maritime traffic, there is no further information available indicating the establishment of a blockade that would satisfy the notification requirement, such as an announcement of the commencement, location, and extent of the blockade. Also, the warnings of NAVAREA III (responsible for the Black Sea area) issued respecting mined areas (NAVAREA III 2022/0118 and 2022/0092) and other danger areas because of ongoing military operations (NAVAREA III 2022/0093) do not refer to the existence or notification of a Russian naval blockade. Neither does the IMO, which appears seriously worried about the safety of seafarers in the area and has pled for a maritime corridor to ensure that merchants can safely leave ports with their vessels. Apart from an unspecified announcement of suspension, nothing more indicates that Russia has established a blockade that might give Russian naval and air forces enforcement powers against merchant vessels.

Effectiveness and Impartiality 

Effectiveness and impartiality aim at stopping all maritime traffic irrespective of flag, including merchant ships of the blockading power (San Remo Manual, §100). The Sea of Azov is of considerable size, spanning about 360 km by 180 km. The ports in the Azov Sea are not only Ukrainian, but also include Russian ports still in operation. Geographical features allow the sea to be easily closed off by blocking the Kerch Strait. It has been reported, however, that traffic through the Strait is not suspended, but rather minimized. Furthermore, vessels are indeed massing at the approaches of the Kerch Strait. Meanwhile, Russia is allowing ships to leave the Sea of Azov to the Black Sea. As one source describes it, “Kerch Strait is closed for vessels passing north into the Sea of Azov, but vessels heading south are permitted to transit.”

Firstly, this would indicate that Russia is not blocking all traffic and is not applying a blockade impartially. Secondly, if it did, one should question whether blocking the entrance of the Sea of Azov amounts to blocking the ingress and egress of all maritime traffic from the enemy ports or coasts, having in mind again that the Sea of Azov is considerable in size with several commercial ports, including Russian ports. The challenge of leaving port is rather a combination of an announcement of suspension of navigation, threats, security, logistical challenges, and a restrictive entrance procedure at the Kerch Strait.

It appears, therefore, that although different factors have effectively minimized maritime traffic into and from the Ukrainian ports in the Sea of Azov, Russia has not established a naval blockade in the Sea of Azov. As a consequence, Russia cannot invoke any belligerent rights that may derive from a legally established blockade to enforce a blockade against vessels.

Operational Maritime Zones (MOZ)

If not a naval blockade, another concept we might look into is a maritime zone. The concept of maritime zones, used previously during the Falklands/Malvinas and the Iraq-Iran conflicts, hasn’t quite crystalized as a matter of law. Its main purpose is to manage maritime battlespace in an area where belligerent naval operations take place. The suspension of navigation in the Sea of Azov, and blocking inward navigation, would arguably fit somewhat better as a maritime zone rather than a naval blockade.

Regarding the legal character of zones, it is argued that the belligerent—in order to fight, minimize neutral interference, and maximize security of its assets—is allowed to control shipping within the vicinity of its operations (San Remo Manual, §108). In other words, establishing such as a zone interferes with the freedom of navigation guaranteed under Article 87 of the Law of the Sea Convention. This is quite imaginable, for example, when an amphibious fleet is preparing an assault on a coastline to attack Berdyansk. But the extent to which the establishment of a maritime zone can be justified, in this case affecting the whole Sea of Azov, depends on the necessity and proportionality of such an act, balancing military requirements against impact on navigation for other users of the sea.

In any case, even if the suspension of navigation in the Sea of Azov should be considered as a form of maritime zone, it still does not absolve a belligerent from its duties under the law of armed conflict, nor does Russia acquire any belligerent rights under the law of blockade. Merchant vessels are therefore still exempt from attack.

The Wider Maritime Dimension

An earlier post in this symposium pressed for doing away with belligerent rights at sea for the aggressor. Whatever one might think of this option, belligerent rights at sea still exist. We can conclude that, at this stage of conflict, the instruments of the law of naval warfare are still left unused.

But there are some challenging “what ifs.” For instance, what if Russia decides to use its belligerent rights under the law of naval warfare? What if Russia decides to publish contraband lists? Would it restrict any arms shipments to Ukraine from the sea? Obviously, no shipment could possibly arrive from the sea to Ukraine if a naval blockade were to be imposed, but must we still accept that the doctrine of continuous voyage on ultimate destination applies if these shipments first arrive in the port of Rotterdam and are then transported over land or air to Ukraine? And what if a convoy of neutral warships protects against visit and search of transporting vessels on which contraband is being carried? The possible issues to consider in the war at sea might just be wider than the Black Sea Basin alone but could start already off the coasts of our own States.

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Commander Martin Fink is a legal advisor in the Royal Netherlands Navy and research fellow at the Royal Netherland Defence Academy. He currently holds the position of Head of Legal Affairs of the Royal Marechaussee.

Photo credit: Nic Redhead via Flickr