The ICRC Casebook defines “blockade” in the following way:

An operation involving naval and air forces by which a belligerent completely prevents movement by sea from or to a port or coast belonging to or occupied by an enemy belligerent. To be mandatory, that is, for third States to be obliged to respect it, the blockade must be effective. This means that it must be maintained by a force sufficient to prevent all access to the enemy coast. The belligerent must declare the existence of the blockade. The belligerent must also specify and the starting date, geographical limits of the blockaded territory and time allowed to neutral vessels to leave. This declaration must be notified to all neutral Powers and to the local authorities.

Back in February, Russia issued a warning that significant portions of the Black Sea were closed to commercial traffic. According to US intelligence reports, the Russian navy seeks to control a significant portion of the Black Sea, the Sea of Azov, and is conducting navel activities along the southern coast of Ukraine and the Crimean Peninsula – which it illegally annexed and has occupied since 2014. However, Russia’s warning about commercial traffic doesn’t specify a starting staring date, geographical limits, nor time period for neutral ships to leave. So, while Russia may be able to prevent access to Ukrainian ports, it’s not obvious its actions meet the legal standard for a blockade.

Nevertheless, there may be good political reasons for overtly challenging Russia here. There are escalation worries that need to be taken seriously.

That said, there is a definite humanitarian issue involved her that needs to be taken seriously. According to the United Nations, global food prices are nearly 30% higher than this time last year. The World Bank is releasing approximately $12 billion in support of food insecurity programs. Russia and Ukraine together account for about 30% pf the world’s supply of wheat. There are approximately 20 million tonnes of grain stuck in Ukrainian ports because of Russia’s invasion and Ukraine has accused Russia of stealing 400 000 tonnes of wheat and farm equipment and shipping it back to Russia.

Of course, the Russian government denies these claims. While the US Secretary of State Antony Blinken has accused Russia of weaponizing food and holding grain for millions of people around the world hostage, Russia’s UN Ambassador Vassily Nebenzia has accused Ukraine of preventing ships from leaving because of its mining of Ukrainian ports. Though Russia has made overtures to allowing ships carrying grain to leave, it will only do so if sanctions are lifted. The issue of sanctions is beside the point, though, because they already make an exception for Russian exports of food.

So, how should the world respond? The US has rejected direct military involvement in the issue and rightly so for the escalations worries already mentioned. While the European Commission has proposed using rail to transport Ukrainian grain out of the country, these could be targeted by Russian military operations. Turkey has responded by Montreux Convention which regulates the access of warships to the Black Sea but Russia can easily use commercial vessels to get around this.

Lithuania – backed by the UK – has proposed a navel “coalition of the willing” to get Ukrainian grain out of the country, while explicitly saying NATO should not be involved. Given the humanitarian nature of the food crisis, this policy makes sense. Russia has said it is ready to provide a “humanitarian corridor” to ships carrying food from Ukraine, but it will only do so in exchange for the lifting of sanctions. However, the sanction should not be lifted. Russia is in violation of one of the most important norms of the post-World War II era – the use of force to take territory. We must remain united against Russian aggression.