As scholarly disciplines go, geopolitics is unusually controversial. In the mid-century United States, the term – or at least its German version, ‘Geopolitik’ – tended to conjure images of a flint-eyed Nazi, revolving a globe and fantasising about conquest. In the modern democratic West, it is quite reasonably criticised for sketching lofty concepts on empty maps. In his 1919 book Democratic Ideals and Reality, one of its founding thinkers, the British academic and politician Halford Mackinder, even invited his readers to view the earth from the moon.
Yet, as the crisis in the Strait of Hormuz has brought sharply home, geopolitics also offers useful ways of thinking about the intersection of, well, geography and politics. The tight sea route from the Persian Gulf out into the Indian Ocean, where the Musandam Peninsula forces ships towards the Iranian coast, is a classic example of a longstanding geopolitical concept: the chokepoint.
This denotes a narrow stretch of sea vital to shipping lines, and vulnerable to closure through the threat of attack. These accidents of geography can radically increase otherwise weak states’ power, whether through direct military advantage, or by allowing them to inflict the kind of pain that is beginning to course through our economies. Even non-state actors can now have a huge impact, if tooled up with enough naval mines, anti-ship missiles and drones, as the Iran-backed Houthis have demonstrated in the Bab-el-Mandeb Strait, which links the Red Sea to the Gulf of Aden. In 2023, 8.7 million barrels of oil reportedly passed this way each day; in 2024 that total was more than halved.
With the rise of Chinese exports, the Strait of Malacca between the Malay Peninsula and Sumatra now carries almost a third of world trade, but remains vulnerable to attack by states and terrorists alike. In the Arctic, global warming is opening up new shipping routes, and with them, new chokepoints. In May 2019, Theresa May discovered the importance of chokepoints to her cost when she authorised the detention of an Iranian-owned oil tanker off Gibraltar – another chokepoint – without taking steps to protect British ships in the Strait of Hormuz. A few weeks later, the Iranians duly seized a British-flagged tanker.
None of this is new. The vital importance of chokepoints was highlighted in 1904, when the British Empire was in its pomp, by the innovative British naval strategist, Admiral ‘Jacky’ Fisher. He proclaimed that ‘five keys lock up the world!’ – the Channel, Gibraltar, Alexandria, the Cape of Good Hope and Singapore – and boasted that all of them were in Britain’s grip.
This strategic thinking was integral both to British imperial dominance – and, by 1904, to America’s bid to emulate it. By this point, the United States had a Fisher of its own: a pioneering theorist of ‘seapower’. Captain Alfred Thayer Mahan was a bookish naval veteran, who preferred the lecture theatre to the real-life military version. In the course of his studies, he examined how a minor island in the north-east Atlantic had managed to punch so far above its weight.
In The Influence of Sea Power upon History 1660-1783 (1890), Mahan noted the vital importance of Britain’s control over the Channel – and with it, the route to northern Europe; likewise, by holding Gibraltar, it could choke off access to the Mediterranean. If a canal was finally carved through the isthmus of Panama, Mahan argued, the position of the US towards it would be similar to Britain’s to the Channel.
Mahan’s work had a huge influence on the imperial ambitions of Theodore Roosevelt, and his support for America’s acquisition of strategic naval bases from the Philippines to Hawaii to Cuba. As David S. Brown notes in a new biography, Roosevelt devoured Mahan’s study of seapower in two days, then declared it ‘the best and most important’ book on naval history in – appropriately – the Atlantic. Roosevelt drove the US construction of the Panama Canal; when it finally opened in 1914, it served to underline the relevance of the chokepoint concept. Other rising, would-be imperial powers such as Germany and Japan seized on Mahan’s thinking, too.
Over time, all this began to date. The advent of intercontinental ballistic missiles rendered these early geopolitical ideas rather quaint. In 1977 President Carter agreed to return the canal to Panama, in a treaty approved by the Senate. By the warm new dawn that followed the end of the Cold War, the stormy bluster of a Roosevelt and the icy cynicism of a Mahan seemed far in the past. In the globalised world of offshore manufacturing and just-in-time supply chains, talk of ‘chokepoints’ might have sounded rather paranoid.
Yet here we are again. China has been closely studying Mahan’s work for years, just as the Japanese did 120 years ago, and its companies have acquired a foothold or more in the English Channel and the Panama Canal. It has made its presence felt in the Luzon Strait between the Philippines and Taiwan. And then there’s Iran’s assertion of power in the Strait of Hormuz.
Given all this, America should not have landed itself in a situation where it has been caught out so predictably by Iran’s in-built geographical advantage. Especially as, very recently, it was apparently still aware of the importance of chokepoints. No sooner had he won the 2024 election than President-elect Trump threatened to retake the Panama Canal. Once in office, the new administration hired a historian called Jerry Hendrix, author of Theodore Roosevelt’s Naval Diplomacy, to advise the National Security Council. According to the maritime news site gCaptain, Hendrix has ‘a deep understanding of Mahanian strategy’, and was involved in drafting an executive order which revealed ‘an aggressive strategy aimed at breaking China’s economic grip on global shipping routes’, partly by pressuring America’s allies ‘to impose tariffs and trade restrictions on Chinese-built ships’.
At the same time, the US Federal Maritime Commission started investigating the ways foreign governments and companies could weaponise the English Channel, the Malacca and Singapore Straits, the Northern Sea Passage, Panama Canal, Strait of Gibraltar, and Suez Canal (but curiously, not the Strait of Hormuz). And, in March 2025, the administration launched an attack on the Houthis in a bid to break their grip on the Bab-el-Mandeb Strait. In what was surely a nod to the cavalry brigade Teddy Roosevelt commanded in the Spanish-American War, the operation was even dubbed ‘Rough Rider’.
Hendrix, however, has since left the National Security Council, and, in whatever preparation there was for the attack on Iran, the risk that Tehran could choke off a huge part of the world’s energy supplies appears to have been forgotten.
Geopolitical thinking can certainly lead to hubristic grandiosity, but ignoring it can have a similar effect. If Trump is going to ape America’s domineering adventures of the late 19th century, he should have more of an eye on the thinking that was guiding it.
