The Maritime Safety Committee (MSC) of the International Maritime Organization (IMO) held its 111th session in London in May. During the meeting, amendments were adopted to the mandatory reporting systems for ships transiting the two principal Danish Straits for international shipping, the Sound and the Great Belt. The reporting systems “In the Sound Between Denmark and Sweden” (SOUNDREP) and “In the Storebælt (Great Belt) traffic area” (BELTREP[TH1] [MK2] ) were initially designed to ensure navigational safety and environmental protection. However, the recent changes expand their original scope.
The amendments to SOUNDREP and BELTREP will require ships to provide details of their mandatory insurance for maritime claims and civil liability certificates. Previously, reporting such information was voluntary, but the revisions now make it an obligation for ships passing through the Danish Straits. The update is regarded to address growing concerns posed by the shadow fleet sailing through the Danish Straits, although the IMO itself has not formally made this classification. The Finnish Government characterised this amendment as a measure that seeks to ensure that the shadow fleet vessels are appropriately insured. This includes coverage for oil spill incidents, a growing concern across the Baltic Sea region. While the revised versions of SOUNDREP and BELTREP were not supported by some delegations, notably China and Russia, the updated resolutions were adopted, and they will enter into force approximately six months after their approval in May.
The Danish Straits as a Key Route for Russian Oil Exports
The Danish Straits – consisting of the Sound (Øresund), the Great Belt (Storebælt) and the Little Belt (Lillabælt) – connect the Baltic Sea to the North Sea. They serve as pivotal maritime routes for vessels entering or leaving the Baltic Sea, connecting the region to global markets. It has been estimated that the Straits handle approximately 70,000 vessel transits annually.
The U.S. Energy Information Administration (EIA) classifies the Danish Straits among the world’s eight major oil transit chokepoints. Their importance as such has only increased following Russia’s full-scale invasion of Ukraine in 2022. The maritime routes through the Baltic Sea have become a critical lifeline for the Russian economy and therefore, for its war against Ukraine. According to the German Institute for International and Security Affairs (SWP), approximately 48% of Russia’s oil exports are transported via the Baltic Sea.
Due to international sanctions, Russia has relied more heavily on ageing and poorly maintained vessels to transport its oil exports. Ships of this type are known as the Russian shadow fleet. In a paper published by the European Parliament, it was estimated that between January and August of 2024, the number of shadow fleet vessels sailing through the Danish Straits increased by 277% in comparison to the same period in 2022. Although operations occur globally, the shadow fleet’s presence in the Danish Straits is particularly significant.
The Danish Straits’s Strategic Potential
The vessels that are part of the Russian shadow fleet have become a pressing issue in the Baltic Sea, increasingly been linked to acts of sabotage and espionage. However, holding them accountable is difficult since most of the illicit activities, such as damage to submarine cables, are difficult to attribute to an intentional act. The North Atlantic Treaty Organization (NATO) has increased its presence in the region to prevent attacks on critical maritime infrastructure from continuously occurring. Although the heightened presence of NATO has brought a better sense of security to the region, it has not prevented the shadow fleet vessels from operating in the Baltic Sea.
Since the Danish Straits are the main gateway for the Russian shadow fleet, it is an ideal point to monitor vessel traffic entering and leaving the Baltic Sea. Despite widespread support among the Baltic Sea coastal states for measures to deter the shadow fleet, some countries have remained more reluctant due to economic interests. Particularly, Denmark has shown hesitance towards actions that could negatively affect its national commercial interests, especially those of Maersk. Due to economic and security concerns, countries have relied on cautious approaches to counter the shadow fleet.
Amendments to the reporting systems of SOUNDREP and BELTREP represent a careful attempt to better oversee the movements of the shadow fleet. Although the revisions have not been declared by IMO as a straightforward action against the Russian shadow fleet, they have been framed as such by many of the Baltic Sea states and others. In practice, vessels passing the Danish Straits are now required to report information about their insurance certificates as part of the mandatory reporting system. The European Parliament states that many shadow fleet vessels use obscure or offshore insurers rather than internationally recognised ones. The requirement to report insurance information will make it more difficult for the shadow fleet with questionable arrangements to avoid attention.
As these amendments are not yet in effect, it remains to be seen how the revised versions of SOUNDREP and BELTREP will apply in practice and whether they will have an impact on the shadow fleet traffic in the Danish Straits.
A New Frontier in the War?
The strategic use of maritime straits has attracted growing interest following the conflict between the United States, Israel and Iran. The Strait of Hormuz has become a prime example of how global maritime chokepoints can be effectively leveraged. By contrast, the Danish Straits have been used far more cautiously. The use of the Danish Straits for Western sanction enforcement is limited by economic considerations and the fear of escalation. Although the updates on the mandatory ship reporting system can help in tracking the shadow fleet, the revisions are by no means sufficient to deter them.
While the oil exports through the Strait of Hormuz have been disrupted, the demand for Russian oil has increased, making the Danish Straits ever more vital. However, the current geostrategic use of the Danish Straits remains limited, even with the new amendments.
