Strait of Hormuz blockade: How the US-Iran war disrupted a global energy lifeline

Summary

The Strait of Hormuz, one of the world’s most critical energy chokepoints, once carrying nearly a fifth of global oil and gas, has been pushed to the brink of paralysis following the outbreak of the US–Iran war in early 2026. What began as a rapid military escalation soon spilled into the waters of the Gulf, where both Iran and the United States imposed competing restrictions. While no formal, universally recognised blockade was declared at first, the scale of attacks, threats, and rising insurance risks effectively shut down commercial shipping. What followed was a steady tightening of control, marked by strikes, warnings, selective permissions, and eventually, a dual blockade that reshaped global trade flows. Here’s a timeline of how it all unfolded: War breaks out, shipping feels immediate shock The crisis began on February 28, 2026, when the United States and Israel launched coordinated air strikes on Iran under Operation Epic Fury, targeting military and nuclear infrastructure. Iran retaliated swiftly with missile strikes across the Gulf. Within hours, the conflict spilled into maritime space. Iran’s Revolutionary Guard (IRGC) began issuing radio warnings to vessels in the Strait of Hormuz, effectively signalling that passage would no longer be safe. By March 1–2, multiple vessels had already come under attack. Oil tankers and cargo ships were hit by drones and projectiles, causing casualties, including Indian crew members, and forcing evacuations. Even before any formal declaration, shipping traffic dropped, with early data showing a 70 per cent reduction in movement. Story continues below this ad “Closure” without declaration: risk makes the Strait unusable On March 2, Iran officially confirmed that the strait was “closed” and warned that any ship attempting to pass would be targeted. However, the closure was not legally formalised as a blockade. Instead, it became functionally shut down due to escalating risks: – War-risk insurance premiums surged – Coverage was withdrawn altogether for key dates – Crews were given the right to refuse sailing through the area By early March, tankers stopped broadcasting tracking signals, and many ships either stayed in port or turned back. The strait remained technically open, but practically unusable. Story continues below this ad Attacks escalate, control tightens By March 4, Iran claimed it had achieved complete control of the Strait. Attacks intensified and multiple vessels were damaged or set on fire while drone and missile strikes expanded beyond the strait into the wider Gulf. A major attack on a tanker near Kuwait caused an oil spill, signalling geographic escalation. By March 12, at least 16 confirmed attacks on shipping had been reported, along with several suspicious incidents. Selective access: Iran allows “friendly” nations Despite the closure, Iran began allowing limited passage to ships from countries it considered neutral or supportive. Countries that were granted access included – China, India, Russia, Pakistan and Iraq. Humanitarian shipments and fertiliser cargo were also permitted following international pressure. This marked a shift from total disruption to controlled, selective access, turning the strait into a geopolitical filter rather than a fully sealed route. Expanding conflict and maritime chaos Through mid-to-late March, maritime security in the region deteriorated further as ships continued to be struck by drones, rockets, and gunfire, while several vessels were seized or forced to remain anchored under threat. Reports also indicated the deployment of naval mines, deepening concerns among shipping operators and insurers. As a result, insurance markets declared the wider Gulf a high-risk zone, pushing operational costs sharply higher and discouraging transit. Even alternative routes through Oman’s ports and regional pipeline networks offered only limited relief, as they were either insufficient in capacity or exposed to emerging threats. In response, a few countries, including India and Pakistan, began deploying naval escorts for commercial vessels, but these efforts remained limited in scale and heavily resource-intensive, falling short of restoring normal shipping flows. Story continues below this ad US steps in: mine-clearing and strategic push The United States further escalated its maritime involvement by deploying US Navy ships into the Strait of Hormuz to conduct mine-clearing operations, describing the move as essential to maintaining “freedom of navigation” in international waters. Iran, however, strongly opposed the presence of foreign military forces in the area and warned that any such deployment would be treated as a trigger for retaliation. At the same time, reports emerged suggesting that Iran had lost track of some of the naval mines it had deployed, further complicating efforts to stabilise the waterway and reopen the route for safe commercial shipping. Dual blockade emerges Following failed diplomatic efforts, the United States formally declared a naval blockade of Iran, significantly widening the scope of the maritime confrontation. Under this policy, US forces began intercepting vessels linked to Iranian trade, particularly those entering or leaving Iranian ports, while maintaining that neutral commercial transit through the Strait of Hormuz would still be permitted. Iran, in turn, rejected the move and warned that any foreign military enforcement in the region would be treated as a violation and met with force. This led to a dual-control situation in the waterway, where Iran attempted to regulate access through threats and selective permissions, while the United States sought to restrict Iranian-linked shipping through enforcement actions tied to its broader blockade strategy. Strait “open” in theory, closed in reality By late April and early May, sporadic attacks on vessels continued to be reported, keeping maritime security in the region fragile and unpredictable. Commercial traffic through the Strait of Hormuz remained minimal as heightened insurance premiums, persistent security threats, and operational uncertainty deterred most shipping operators from using the route. Although a few vessels still managed to pass under naval escort or through negotiated arrangements, these movements were limited and inconsistent. As a result, the Strait of Hormuz remained effectively closed in practice, not through a single formal declaration, but due to the cumulative impact of sustained military pressure, economic risk, and ongoing instability. The bigger picture The blockade of the Strait of Hormuz has not taken the form of a conventional wartime closure. Instead, it has emerged as a layered disruption shaped by military action, economic pressure, and political signalling. Rather than a clear and formal shutdown, the situation has evolved into a gradual suffocation of one of the world’s most critical trade arteries. In this environment, fear has effectively replaced formal rules, risk has overtaken legality, and access has become increasingly dependent on geopolitical alignment. The wider consequences, ranging from volatility in global oil prices to disruptions in supply chains and shifting geopolitical alliances, continue to unfold and remain highly uncertain.