Capability
The Power to Close the Sea
What is the central argument of “The Power to Close the Sea”, and why does it matter for European defence and dual-use markets?
The Power to Close the Sea: Maritime power is never decided on the open sea. Defence-finance analysis; 12-page sourced DFM PDF report.
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Original DFM publication · DFM Analysis report · 2026-06-16
Maritime power is never decided on the open sea. The horizon cannot be held, blockaded, or taxed; what can be held are the places where the sea narrows to a line — the straits and passages through which the traffic of whole basins must funnel.
It is there, not on open water, that the fate of every thalassocracy is settled, because it is there that a single power on the shore can do the one thing the open sea forbids: it can close. The history of sea empires is, in this sense, a history of chokepoints — of who holds the doors, and of what follows when a door changes hands.
This analysis answers: What is the central argument of “The Power to Close the Sea”, and why does it matter for European defence and dual-use markets? How does the analysis address i. The Strait at the Origin? How does the analysis address iI. A Sea of Many Closures? What does this mean for European defence funding, procurement and investment decisions?
Key takeaways
- The history of sea empires is, in this sense, a history of chokepoints — of who holds the doors, and of what follows when a door changes hands.
- How does the analysis address i.
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Original DFM analysis
The Power to Close the Sea
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FAQ
What is The Power to Close the Sea?
The horizon cannot be held, blockaded, or taxed; what can be held are the places where the sea narrows to a line — the straits and passages through which the traffic of whole basins must funnel.
Why does The Power to Close the Sea matter for European defence?
It is there, not on open water, that the fate of every thalassocracy is settled, because it is there that a single power on the shore can do the one thing the open sea forbids: it can close.
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