Strategic Chokepoint With a History of Tension
The Strait of Hormuz is a narrow waterway connecting the Persian Gulf to the Gulf of Oman. It provides the only sea passage from the gulf to the open ocean, making it one of the world’s most strategically important maritime chokepoints. A large share of global seaborne oil trade and liquefied natural gas shipments passes through it each year. Several Gulf countries, including Iraq, Kuwait, Qatar, Bahrain, and the United Arab Emirates, rely on the strait as their sole maritime route for exports. Any disruption to traffic there can cause severe supply shortages for Europe and Asia.
Iran has periodically threatened to close the strait during periods of heightened tension. The most serious precedent came during the Iran-Iraq War, which ran from 1980 to 1988. Iranian forces attacked oil tankers in the waterway during that conflict, prompting the U.S. Navy to launch Operation Earnest Will from 1987 to 1988, a mission to reflag and escort Kuwaiti tankers through the strait. The war ended in 1988 with a United Nations-brokered ceasefire, but the pattern of coercion had been set.
From Threats to Seizures: Escalation Over Two Decades
In more recent years, Iran has alternated between threats and direct action. In 2012, Tehran warned it would shut the strait in response to U.S. and European Union sanctions targeting its oil exports. The threat did not materialize into a full closure, but it established a pattern of coercive rhetoric. After the United States withdrew from the Joint Comprehensive Plan of Action (JCPOA) in 2018 and reimposed sanctions, Iran shifted from threats to action. In July 2019, Iranian forces seized several oil tankers in the strait, including the Stena Impero.
The U.S. response came in November 2019 with the formation of the International Maritime Security Construct (IMSC), a coalition of nations tasked with protecting shipping in the region. The United Nations Security Council held emergency sessions on the strait in 2019 and again in 2020, reflecting growing international concern over the safety of one of the world’s most vital energy waterways. Those sessions, however, did not produce a sustained military intervention or diplomatic breakthrough.
Now, the current closure announced on April 28, 2025, represents a further escalation. Iran’s leadership has not detailed the duration or conditions of the closure. The Trump administration has not publicly announced a new naval mission comparable to Operation Earnest Will or the IMSC, though the Pentagon is understood to be reviewing options.
Uncertainty Remains as Markets Brace for Impact
The stakes for the global economy are high because the strait is critical for energy supply chains. Any extended blockage could ripple through markets worldwide. The United Nations Security Council has not yet scheduled an emergency session for the current crisis, but past precedent suggests one may be called. For now, shipping companies and oil markets are watching for any sign of naval escort operations or diplomatic breakthroughs.
The situation remains fluid. Previous crises, including the Iran-Iraq War and the 2019 seizures, did not lead to a sustained closure. Early findings suggest the same caution applies today. Policymakers and market analysts are advising against drawing firm conclusions before more information emerges. The encouraging part, based on history, is that Iran’s most aggressive moves in the strait have so far been temporary or contained. Whether the 2025 closure follows that pattern or marks a new, more dangerous phase remains to be seen.
