Control of the Straits

In memory of Afonso de Albuquerque, Lion of the Seas, who demonstrated that strategic intelligence surpasses brute force, and that control of the sea is control of the world.

And to all those who navigate impossible straits with insufficient resources and unlimited vision.

- Hermínio Cerqueira
The Sea as an Instrument of Global Power
1.1 The geometry of sea power

The ocean is not a void. On the contrary, it is the oldest and most persistent axis of power that humanity has built, a three-dimensional space where trade routes, energy supply lines, industrial logistics chains, and vectors of military projection intersect. Understanding maritime power requires, first and foremost, recognizing its specific geometry: unlike land power, which is exercised in contiguity and knows borders, friction, and physical barriers, power over the sea tends towards ubiquity—whoever dominates it can, in theory, appear at any point on the ocean's surface, with concentrated force and unrestricted mobility. This fundamental asymmetry between land dominance and maritime dominance is the basis of all strategic theory that has developed from the 16th century to the present.

The geometry of maritime power is organized around three analytical categories that interpenetrate without ever becoming confused: access, control, and denial. Access refers to the ability to freely use the sea—for commercial purposes, for projecting force, or for strategic surveillance. Control implies the ability to regulate the use of the sea by third parties, distinguishing between allies who are granted passage and adversaries who are denied it. Denial, in turn, refers to the ability to prevent an adversary from using the sea, even without the need for absolute control—it is enough that the imposed cost is high enough to change the adversary's behavior. The 2026 Hormuz crisis is, in essence, a combined exercise of selective control and denial: Iran did not close the strait to all navigators, but instituted a discriminatory regime that distinguished between "hostile" and "friendly" nations, imposing tolls in yuan on some and granting free passage to others (CSIS, 2026).

The geometry of maritime power is also organized vertically in historical time. Empires that understood the sea as an instrument of power—Athens, Carthage, Venice, Portugal, the Netherlands, Great Britain, the United States—shared a structural characteristic: the ability to convert naval mobility into commercial wealth and, conversely, commercial wealth into sustained naval capacity. Paul Kennedy called this cycle of mutual reinforcement the "material foundation of imperial power" (Kennedy, 1987), and its absence is often the prelude to decline. Fourteenth- and fifteenth-century China exemplifies the other side: Zheng He led seven major expeditions to the Indian Ocean and the east coast of Africa between 1405 and 1433, but the Ming state chose to withdraw from the sea and destroy fleet records, spontaneously surrendering the maritime advantage to the Europeans who would arrive there a few decades later.

Maritime power is neither static nor automatic. It depends on maintaining a set of conditions that Alfred Thayer Mahan first systematized with scientific rigor in 1890, and which subsequent authors have deepened and revisited in light of technological and geopolitical transformations. What is important to emphasize in this analytical overview is that the sea is simultaneously a resource and a vulnerability: a resource for those who dominate it, because it allows global projection at a relatively low cost; a vulnerability for those who depend on its routes without having the means to defend them.