TEHRAN, July 12 — For the first time in modern history, Iran has declared an indefinite closure of the Strait of Hormuz, the narrow waterway through which a significant portion of the world’s seaborne oil passes. The announcement, made by state media on April 28, 2025, marks a dramatic escalation in a long-running confrontation between Tehran and the West. The move is not without precedent.
Iran has periodically threatened to shut the strait as a strategic lever in its conflicts with the United States and regional adversaries. During the Iran-Iraq War, the so-called Tanker War phase from 1984 to 1988 saw Iran attack oil tankers and shipping in the Persian Gulf.
That campaign prompted the United States to launch Operation Earnest Will, a naval escort mission that ran from 1987 to 1988.
A history of threats and seizures
In 2008, the Islamic Revolutionary Guard Corps Navy warned it could close the strait if Iran’s nuclear facilities were attacked. By December 2011, Iran’s Vice President Mohammad Reza Rahimi threatened to block oil shipments through the waterway in direct response to U.S. and European Union sanctions targeting Iran’s oil exports. The U.S. Fifth Fleet responded bluntly, stating that such a move would be considered an act of war.
The IRGC Navy has also conducted exercises in the strait, including the Great Prophet 9 exercise in 2011, which tested anti-ship missiles and fast-attack craft. In 2019, after the U.S. withdrew from the Joint Comprehensive Plan of Action and reimposed sanctions, Iran seized several tankers in the strait, including the British-flagged Stena Impero in July of that year.
But the current closure, announced by state media on April 28, 2025, is different. It is the first indefinite closure Tehran has ever formally declared.
What the closure means for communities across Asia
For communities across Asia, particularly in countries heavily dependent on imported energy, the closure carries immediate and practical consequences. The Strait of Hormuz is a chokepoint for oil and liquefied natural gas shipments bound for Japan, South Korea, India, China, and Southeast Asia. Any sustained disruption threatens to raise fuel prices and strain supply chains that families and businesses rely on.
Closer to home, the Philippines imports the vast majority of its oil, much of it transiting through the strait. Rising fuel costs could mean higher prices for transport, electricity, and basic goods for Filipino households.
Across the region, governments are watching nervously, weighing diplomatic responses against the risk of further escalation. The U.S. Fifth Fleet, based in Bahrain, has not yet announced a formal response to the indefinite closure. But given its 2011 warning that blocking the strait would be an act of war, the situation remains volatile.
For now, the world waits to see whether diplomacy or confrontation will prevail in the waters that connect the Persian Gulf to the open ocean.
