How Can NATO Overcome Russia’s Black Sea Blockade?

Moving in unison: A US Navy destroyer and a Ukrainian Navy frigate in the Black Sea. Image: US Navy Photo / Alamy

Following the breakdown of the grain deal between Russia and Ukraine, how can NATO partners help to mitigate the impact of Russia’s effective blockade of Ukrainian ports?

In a recent article, Admiral James G Stavridis, the former NATO SACEUR, suggested that a NATO-led convoying system in the Black Sea could go some distance towards alleviating the costs of Russia’s de facto blockade of Ukraine following President Vladimir Putin’s withdrawal from the grain deal. While Stavridis makes a number of important points, a convoying system would be an impractical solution to the challenges posed by a blockade, one which would incur significant risks for uncertain gains. Instead, an approach to meeting the challenge of the blockade should be built on two pillars: circumvention in the short term, and a wider effort aimed at coercing Russia back into a settlement in the medium term.

The Problem with Convoys

There are several issues with using the Iran–Iraq Tanker War of the 1980s as an analogy for a potential full-scale convoying operation in the Black Sea. The first issue is that to a far greater extent than the Tanker War, the outcome of a contest to move grain through Ukrainian ports will be determined by the attitudes of insurers. US convoying operations during the Tanker War mitigated but did not eliminate the high war risk premiums demanded by insurers, not least because they were restricted to reflagged Kuwaiti vessels. The reason that neither Iraq nor Iran was able to seriously impact the other’s oil exports and the global economy was that the profit margins involved in moving oil justified the transit even in the face of higher insurance rates – something that is not as true for grain. Moreover, Iraq was able to circumvent the Iranian blockade using overland pipelines to Turkey and Yanbu in Saudi Arabia. While convoying was a useful means of both defending the principle of freedom of navigation and forestalling the Soviet Union’s efforts to increase its influence in Kuwait, its economic impact was marginal.

Today, the major challenge facing Ukraine is that insurers’ risk perceptions will likely drive a spike in war risk premiums, which could make movement in the Black Sea effectively unprofitable, or even lead to coverage being withdrawn. While convoys could resolve this underlying challenge by reassuring shipowners, they could also have the opposite effect. The sight of NATO and Russian assets operating cheek by jowl could just as easily increase perceptions of war risk. Russia could exacerbate this risk through acts of brinkmanship such as risky aerial manoeuvres, much as it has done recently.

The second major issue with convoys is that the Russian threat to shipping in the northern Black Sea is in certain ways dissimilar to the Iranian one. Iran sought to interdict or attack vessels at sea using the assets of its navy and the Islamic Revolutionary Guard Corps (IRGC), making the presence of nearby friendly combatant vessels a useful deterrent. Russia’s fleet has largely avoided the northern Black Sea since the Moskva incident. The risk posed by Ukrainian coastal defence cruise missiles such as the Harpoon and Neptune has largely eliminated the surface vessels of the Black Sea Fleet as a presence in the northern Black Sea. The primary tools of blockade for Russia are naval mines – which it can seed using a range of capabilities including its Kilo-class submarines – and missile strikes on storage sites on the ground. Convoys can usefully deter things such as the interdiction and boarding of vessels, but are of less value in the face of a mine threat. Indeed, in instances such as the Bridgeton incident during the Tanker War, US assets had to form up in columns behind a double-hulled tanker as a defence against mines. The mine challenge could be a basis for deploying mine countermeasures (MCM) vessels – something discussed in the original article – but as will be articulated more fully later, this is a separate consideration from convoying.

The third consideration, acknowledged by figures such as Stavridis, is the degree to which the Montreux Convention constrains policy options. Considering that the aggregate tonnage of all non-Black Sea navies at any given time cannot exceed 45,000 tonnes (around the weight of five Ticonderoga-class cruisers) and that vessels must rotate out of the region after 21 days, the ability of non-Black Sea countries to maintain credible forces in the region will be circumscribed irrespective of whether they are willing to commit more vessels. Of course, a Turkish decision either to void certain restrictions or to participate in a convoy system itself could change this dynamic, but this remains unlikely. A convoy system could only work in practice if it was led by those members of NATO that are also Black Sea states, with a somewhat token presence provided by Allies from beyond the region. This implies that smaller members of the Alliance would bear the lion’s share of the cost and risk – something they are unlikely to do.

There is also a real risk of escalation, as acknowledged. While Russia is unlikely to directly attack a NATO member, there are a number of avenues to inadvertent escalation. For example, if a NATO vessel struck a mine like the USS Samuel B Roberts did during the Tanker War, the Alliance would be faced with an unpalatable choice between escalating or choosing not to attribute the damage (and thus perhaps incentivising intentional efforts to clandestinely attack its vessels). A weaker opponent may act in risk-acceptant ways that draw it into clashes with a stronger rival – as Iran’s IRGC did with the US Navy on several occasions. Brinkmanship by both sides can create room for misunderstandings, as was nearly the case during the Cold War when a Soviet Tu-16 buzzing a US carrier pitched into the sea in an incident which could have been misinterpreted as a shootdown.

A Short-Term Approach: Circumvention and Limited Support to Shipping

There are short-term solutions that adopt elements of the proposals put forward by proponents of a more forward-leaning NATO role, but which do not require the Ukrainians and their partners to run the risks of a full-scale convoying operation.

Foremost among these is circumventing the blockade. Both overland routes and riverine transit via the Danube offer alternatives to the Black Sea. In the past year, Ukraine’s riverine ports such as Izmail have seen a substantial increase in the volume of shipping that they have handled. While not sufficient to completely offset the impact of a blockade, this could substantially mitigate the challenge. Unsurprisingly, these ports have come under sustained air attack by Russia. The challenge of air defence, while complex and resource-intensive, can be resolved by the provision of additional platforms to Ukraine. A more ambitious course could see Ukraine’s partners defend these areas from cruise missiles directly. Given their proximity to the borders of a NATO state, a defensive counter-air mission over these riverine ports need not be framed as an entry into the conflict, but rather as a means of mitigating risk. The fact that such a mission would involve intercepts of missiles and not manned aircraft limits the risk of escalation. To be sure, any such decision would need to be taken alongside efforts to define the geographical limits of NATO support to avoid mission creep.

A second palliative would be subsidising overland transport. Thus far, the costs of overland transport and the reluctance of European states such as Poland to expose their own farmers to competition from Ukrainian produce – which is more price-competitive in nearby countries than it is after a long and costly transit – have meant that the EU’s grain corridors have had limited utility for Ukraine. Subsidising the transit of Ukrainian goods to ensure that they do not stay in EU countries could be a ready fix to this conundrum.

Ultimately, the only long-term guarantee of freedom of navigation in the Black Sea is a settlement with Russia; anything short of this will not solve the problem of war risk premiums

Finally, there is a basis for a more limited approach to directly challenging the blockade. Clearing mines through channels in the western Black Sea could allow some vessels to depart from Odessa, especially if the effort was combined with a bolstering of Ukraine’s ground-based air defences. There is an obvious utility to vessels such as MCM ships, but the value of a wider convoying effort is less clear. Because of the Black Sea Fleet’s restricted freedom of action in the face of the Ukrainian coastal defence cruise missile threat, the risk to vessels at sea will come primarily from mines, and they are likely to be most at risk when they are stationary targets in port.

True, MCM vessels operating on their own would be vulnerable to Russian attack (though Russia’s difficulty in sinking the Ukrainian tank landing ship Yuri Olefirenko at sea demonstrates real challenges with dynamic targeting). It should be noted, however, that even a convoy in the Black Sea would theoretically be at risk of being sunk if Russia wished to invest the resources into doing so. The deterrent to this would be the wider implications of a direct attack on a Western vessel, not the vessel’s own defences. While it might be regarded as counterintuitive to deploy vessels in such a manner, it is worth noting that this is precisely what Western European deployments such as the Armilla patrol did during the Tanker War by utilising naval vessels that were unarmed.

Given their limited tonnage and lack of offensive armaments, MCM could be rotated into the region in larger numbers and with less escalatory risk. The task of navies, then, would be to brief insurers on the fact that the absence of convoys does not mean that channels are unsafe, given the low likelihood of direct Russian interdiction by surface platforms.

With regards to air defences, NATO members such as Greece and Bulgaria which currently operate S-300 batteries could be encouraged to play a role here. Similarly, the US Army’s Iron Dome batteries, which may have some utility against threats such as UAVs, could be donated if – as argued by some – they are deemed unfit for the environments in which the US expects its ground forces to operate.

In conjunction with this, a multilateral effort to provide state-backed insurance could be utilised to further mitigate the financial risk undertaken by vessels’ owners. This is something Iran did to good effect during the Tanker War when it underwrote 15% of the cost of insurance. This contributed to Iran’s oil exports rebounding to pre-war levels by the late 1980s, despite the Iraqi air threat to terminals like Kharg.

Each approach is likely to be extremely expensive and involve diplomatic and financial costs. Countries are loathe to part with capabilities such as air defences, and subsidising transport is likely to be exceedingly expensive. However, the ability of a new Iranian regime to achieve the latter goal in the 1980s demonstrates that it is not impossible, while the former is less diplomatically challenging than organising a multilateral convoying effort.

The Long Term: Coercing Russia into a Settlement

All of the palliatives described above can only work in the short term, however, given the costs involved. Ultimately, the only long-term guarantee of freedom of navigation in the Black Sea is a settlement with Russia; anything short of this will not solve the problem of war risk premiums. The question for Ukraine and its backers, then, is how Russia can be coerced into entering a settlement and respecting it. The importance of the ability to counter an opponent’s blockade with one’s own punitive measures, thus denying them the perception that time is on their side if they only wait, is an enduring lesson of naval combat.

Of course, if Ukraine’s ongoing offensive proves immensely successful, Crimea might cease to be a springboard for Russian coercion, and the country’s Azov ports might open. That said, it is worth planning for a more conservative outcome in which both sides remain deadlocked and Russia seeks to grind Ukraine down through a long-term campaign against the country’s economy.

Ultimately, Ukraine’s ability to compel Russia to re-enter some form of agreement on shipping (even if hostilities continue) will be predicated on its capacity to counter-escalate. There are several avenues by which this might be done. Firstly, Ukrainian forces can contest Russia’s own commercial vessels’ freedom of navigation at or near ports. The uncrewed assets used near Sevastopol could serve as a useful tool to harass shipping, and though Russia would likely deploy countermeasures, this could still drive up insurance rates. Presumably such vessels could also be used as minelayers – though their carrying capacity might be somewhat limited.

In the immediate term, it will likely prove more viable to mitigate the effects of the blockade by circumventing it

Secondly, a more concerted effort could be made to identify and interdict the grey shipping upon which Russia’s own economy depends. Though it is politically and legally challenging to seize vessels on the high seas, states with territorial waters that straddle transit chokepoints can deny these vessels access if they are not suitably insured against environmental risks. NATO countries that currently straddle such chokepoints include the UK and France (in the case of the English Channel and Gibraltar) and Turkey (at the Bosporus). Of course, it is unlikely that a unanimous approach to interdicting such vessels will be achieved, but heightened pressure in this area could still increase the costs for Moscow and contribute to enabling subsequent negotiations.

Perhaps most crucially, however, Ukraine must be able to limit the Black Sea Fleet’s ability to operate out of Sevastopol. The threat of Ukraine accomplishing this could be sufficient to compel Russia to re-enter a settlement. We might consider, for example, how the Houthi movement’s ability to impose costs on its opponents and effectively shut down key ports and cities such as Marib with ballistic missiles played an important role in driving the anti-Houthi coalition towards a settlement in Yemen.

Assuming the current lines stay broadly stable, the Ukrainians would need either cruise or ballistic missiles with a range of over 300 km to achieve this. While it is presently unlikely that the US-made ATACMS will be provided to Ukraine, other options exist. For example, a concerted effort could be made to expand production lines for Storm Shadow – a weapon already in Ukraine, but one that the country must use sparingly.

An alternative would be to use the soil of friendly states to commence the production of indigenous designs such as the Grom-2 ballistic missile in sanctuaries safe from destruction by Russian airpower. More immediate means of contesting Russian commercial ports could include low-cost UAVs, which appear to have been used in Russia itself.

Another capability which could conceivably abet a counter-blockade but which would presently be difficult to manufacture in Ukraine is submersibles capable of carrying torpedoes – something currently being prototyped by, among others, a UAE-based Ukrainian firm. Production lines for such capabilities could be set up on the territory of NATO members which currently sit within the Black Sea, enabling their transfer without the need to violate article 19 of Montreux.

Of course, there are legitimate concerns regarding the escalatory risks involved in giving Ukraine the capacity to act against Russian interests at reach. That being said, generating the capacity to – for example – manufacture missiles for Ukraine will be time-consuming, and could thus give both parties the diplomatic space to re-enter a settlement. Even a latent threat to reinforce Ukraine’s offensive capacity could be useful, irrespective of whether it is acted upon.


Ultimately, there are no ideal solutions to the challenge posed by Russia’s blockade. Though appealing, the obvious immediate palliative of a convoy system is likely to be unworkable in practice. Though many issues impede such a solution, as discussed, its primary flaw is the fact that it does not obviate the most significant challenge facing Ukrainian exports – the fact that high war risk premiums will likely remain in place.

In the immediate term, it will likely prove more viable to mitigate the effects of the blockade by circumventing it. Though costly, circumvention via routes such as the Danube offers the most immediately viable method of limiting – if not quite eliminating – the impact of the blockade. Alongside this, allied navies can make genuine immediate contributions in areas such as mine countermeasures.

In the medium to long term, the most viable route to a resumption of Black Sea shipping from Ukrainian ports is a campaign to progressively increase the pressure on Russia’s own maritime posture in the region, as well as to impose costs in other areas, with a view to eventually reaching a durable settlement which at a minimum separates the issue of freedom of navigation from the wider conflict.

The views expressed in this Commentary are the author’s, and do not represent those of RUSI or any other institution.

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Dr Sidharth Kaushal

Senior Research Fellow, Sea Power

Military Sciences

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