RUSSIA’S de facto declaration of a naval blockade on Ukraine this week marks the first time in decades that one country has unveiled an intent systematically to deny neutral shipping access to another country’s ports.

One would have to go back more than half a century — when Washington imposed a ‘quarantine’ on Cuba during the 1962 missile crisis and Egypt prevented Israeli access to the Straits of Tiran as a prelude to the Six-Day War of 1967 — to find applicable parallels.

Hundreds of third country tankers were hit in the Iran-Iraq war of 1980. But even the repeated strikes did not prevent Iranian and Iraqi oil continuing to find its way onto world markets.

The Kremlin’s recent announcement that vessels in Ukrainian territorial waters will be deemed legitimate military targets, and their flag states considered Ukrainian allies, is completely out of kilter with our very changed post-Cold War world.

Thankfully, there are already indications that such threats were more by way of rhetoric than serious plan of action.

Russia’s ambassador to Washington, Anatoly Antonov, has subsequently stated on social media that no preparations are currently under way actually to attack vessels.

This is a positive, although it would be better to get such reassurances from the Kremlin itself, rather than its diplomatic representatives abroad.

Of course, Russia does not have to sink ships to achieve its desired outcomes. This symbolic interdiction will have real world consequences, with the noises often alone likely to deter any sane shipowner from accepting fixtures.

That makes the move look like an easy win for Moscow. But it may not be in Russia’s longer-term interests, rationally understood.

The incursion into Ukraine in February 2022 was launched in contravention of international law, and its armed forces and mercenaries have credibly been accused of war crimes as part of this ‘special military operation’.

Nevertheless, it bears repeating that blowing up merchant vessels is a clear contravention of international law.

At the very least, ships remain entitled to assert innocent passage as set down under articles 17, 18, 19 and 25.3 of the United Nations Convention on the Law of the Sea.

Any trigger-happy attacks could one day form an addition to the charge sheet if Russian politicians and officials end up in the dock when the invasion is all over.

There is also the question of ethics. The context for this entire debacle is Russia’s decision to end the Black Sea grain corridor initiative as of the past Monday.

The scheme quite literally constituted a lifeline for millions of people in the Middle East, North Africa and parts of Asia, for whom Ukrainian grains are a staple food. It would be immoral to let them starve.

These are some of the very countries in which Russia has been keen to extend its soft power – and, for that matter, hard power – in recent years. The efforts have largely been successful.

Its incursion into Ukraine has met with a surprising degree of acceptance in the global south. Discounted crude has even proved sufficient to overcome memories on the part of some countries with recent experience of colonialism themselves.

Russia is, of course, a major grain producer in its own right, and has promised to take up part of the slack.

But its actions have already provoked a sharp jump in the price of both wheat and corn, which is not how to win friends and influence people.

Food riots could turn currently friendly governments into unfriendly governments overnight. Russia might do better instead to seek a means to resurrect the grain initiative.

Finally, let’s think through the politics. The proposition that the flag states of such ships as might be persuaded to call in Ukraine therefore render themselves Ukrainian allies is entirely ludicrous.

Open registries will have their own diplomatic alignments, and yes, some of the biggest are clearly aligned with Washington.

But they are in business precisely to extend the maximum commercial freedoms to clients. Rightly, they have never displayed the slightest propensity to stop owners from accepting charters they are legally entitled to accept.

Governments of the major flag states should use relevant diplomatic channels to ensure that Moscow is aware of basic commercial reality.

The situation in the Black Sea remains fluid. But legality, humanity and common sense still have the chance to prevail. Let the shipping industry do all it can to ensure they do.