Imagine a deck of cards, each illustrated with a different instrument of economic warfare. Examples include export controls, financial sanctions, and the one currently giving commodity traders nervous breakdowns: halted traffic through the Strait of Hormuz. Each weapon is assigned three scores: one for economic potency, another summarising the scope for self-harm and a third for durability. Call the game Top Trumps: Chokepoints edition.
Start with marine bottlenecks, by which we mean the canals, straits, channels or seas that ships pass through. A study by Lincoln Pratson of Duke University counted 13, estimating that in 2019 roughly four-fifths of the world’s trade flowing between non-neighbouring countries passed through one.
In most cases, the economic damage score associated with choking off these routes would be a lowly two or three out of five. Closing the busy English Channel, for example, would lead trade to reroute around the top of the UK taking several days longer. Closing the Strait of Gibraltar, the Suez Canal or the Bab el-Mandeb strait (connecting the Red Sea and the Indian Ocean) would add as much as a month to some journey times. But ultimately ships should find other paths to their destinations.