Global trade is losing one of its operational certainties: the relative reliability of major shipping routes. Attacks in the Strait of Hormuz, the Red Sea, the Black Sea and the Sea of Azov show how passages essential to the global economy can rapidly become combat zones. Shipping companies are consequently facing mounting pressure to choose between riskier routes and diversions that increase transit times and transport costs.

The economic implications are significant because about 80% of global merchandise trade by volume is transported by sea. Disruption to even one strategic corridor can delay deliveries, temporarily reduce product availability and drive up prices thousands of kilometres away. Energy, food commodities and consumer goods are among the categories most exposed to the consequences of such blockages.

What is new is not only the growing number of crisis areas, but also the weapons being used. Drones and missiles allow smaller military forces to threaten ships, ports and infrastructure with equipment that is relatively inexpensive compared with traditional naval capabilities. David Roche, president and global strategist at Quantum Strategy, described the clashes in the Sea of Azov and the Black Sea as a new war centred on yet another trade bottleneck.

According to Roche, operations in the area represent the first maritime offensive conducted almost entirely with drones, supported by missiles. Ukrainian unmanned vehicles have struck Russian oil tankers, demonstrating how accessible technologies can produce economic consequences disproportionate to their cost. The targets are not limited to the adversary’s military capabilities, but also include its export operations and the infrastructure supporting them.

Quantum Strategy estimates that around 25% of Russian grain exports could be affected. For Russian oil shipped through the Black Sea, the potentially exposed share is estimated at between 25% and 30%. These figures carry international significance because Russia supplies more than one-fifth of the wheat traded on global markets. Prolonged disruptions could therefore have repercussions for food prices worldwide.

Another critical point is the Kerch Strait, which connects the Sea of Azov with the Black Sea. Yevgeniya Gaber, a senior fellow at the Atlantic Council think tank, said Russia’s decision to suspend navigation through the strait at the beginning of the month had effectively closed a vital maritime corridor. The route had become increasingly important as an alternative to the land connection between Russia and occupied Crimea.

The closure affects a diverse range of trade flows. According to Gaber, the Sea of Azov has been used to transport sanctioned crude oil and petroleum products, as well as grain, coal and steel. This combination of energy, agricultural and industrial goods makes the corridor particularly sensitive. A blockade would not remain confined to a single sector but could spread across multiple production and trade chains.

In the Strait of Hormuz, meanwhile, commercial operators must contend with attacks and shifting guidance about the safety of the passage. Government statements that a waterway is open are not enough to guarantee a return to normal conditions. The final decision rests with shipowners, who assess the likelihood of a vessel being struck and the risk that crew members could be injured or killed.

This decision-making autonomy explains why a formally open route may remain underused in practice or accessible only at higher cost. Attacks on commercial vessels have already prompted diversions, increased insurance expenses and higher freight rates. Routes once considered dependable are now being reassessed according to rapidly changing military factors that lie outside normal supply-and-demand dynamics.

Daejin Lee, global head of research, warns against treating Hormuz, the Black Sea and Bab el-Mandeb as separate crises. The emerging picture is one of shared vulnerability across major maritime passages, where a localised attack can affect international supply chains. Route security is therefore becoming a structural component of corporate strategy, alongside fuel costs, vessel availability and delivery times.

It remains unclear how long the navigation suspensions will last and how much of Russia’s oil and grain flows will actually be disrupted. Developments in the Strait of Hormuz will likewise depend not only on official communications but also on shipowners’ practical risk assessments. As long as the danger to vessels and crews remains high, global trade will have to contend with less predictable routes and costs that are increasingly exposed to the course of armed conflicts.