Between hollow rhetoric and war: how sanctions work – and why they often don’t

A sign protesting against Russia’s invasion of Ukraine. Whether sanctions will stop Putin and the Ukraine war, however, remains to be seen. Photograph: Stéphanie Lecocq/EPA

In the year 432BCE, the Athenian empire sought to teach its smaller neighbour, Megara, a punitive lesson after various acts of defiance. Instead of going to war, which would break the peace with Sparta, Athens took the novel path of blocking the Megarians from using all the ports in the region.

It was known as the Megarian decree, and it was arguably the first recorded case of economic sanctions. It was also a failure, at least when it came to fending off a conflict. The Peloponnesian war, pitting Athens against Sparta, erupted a year later, and some ancient historians believe it was triggered by the Megarian sanctions.