A recent U.S. Defense Intelligence Agency (DIA) assessment has sent ripples through global markets, suggesting Iran could keep the Strait of Hormuz closed for one to six months.
This situation didn't emerge from a vacuum. It was triggered by U.S.-Israeli strikes on Iran in late February 2026, prompting Iran to retaliate by threatening to block the world's most critical oil chokepoint. The consequences of this threat became tangible almost immediately, creating a multi-layered crisis that unfolds in three key stages.
First, an economic blockade took shape without a single shot being fired. Maritime insurers, spooked by the escalating risks, canceled war-risk coverage for the region. For any ship willing to take the chance, insurance premiums skyrocketed by over 1,100%. This financial barrier was so high that it effectively halted most commercial traffic, turning a military threat into a commercial reality. The strait, through which about a quarter of the world's seaborne oil flows, fell silent.
Second, the world scrambled to mitigate the supply shock. The International Energy Agency (IEA) responded by authorizing the largest-ever release of emergency oil reserves—a staggering 400 million barrels. While this provides a crucial buffer, it's a temporary one. The math is stark: this reserve can offset a major shortfall for roughly 50 days. If the closure lasts for several months, as the DIA's upper estimate suggests, these stockpiles will run out, leading to severe shortages and even higher prices.
Third, the political and military responses are fraught with complexity and uncertainty. The U.S. has discussed organizing naval escorts to guide tankers through the strait. However, past testimony from U.S. Central Command (CENTCOM) indicates that clearing the area of naval mines—a likely Iranian tactic—is a painstaking process that takes months, not weeks. This operational reality lends weight to the DIA's longer timeline. Compounding the issue are mixed signals from the White House, which has simultaneously talked up military solutions while also suggesting it could end the conflict without reopening the strait, leaving allies and markets guessing.
In essence, the DIA's 1-to-6-month forecast isn't just a worst-case scenario. It's a realistic planning window shaped by the hard realities of insurance markets, logistical limitations of oil reserves, and the slow pace of military countermeasures.
- Strait of Hormuz: A narrow waterway connecting the Persian Gulf to the open ocean, through which about a quarter of the world's seaborne oil passes.
- DIA (Defense Intelligence Agency): The primary U.S. military intelligence agency.
- IEA (International Energy Agency): An intergovernmental organization that advises on global energy policy and coordinates emergency oil stock releases.