The U.S. military and regional allies used a covert "dark fleet" of tankers to move roughly 100 million barrels of oil [1] through the Strait of Hormuz.

This operation marks a significant escalation in the tactical effort to ensure global energy flows while bypassing Iranian surveillance. By utilizing stealth tactics, the U.S. aimed to counter Iranian pressure on the narrow waterway and maintain market stability.

Analysts observed the activity throughout May 2026, noting that nearly 900 outbound tankers [2] went "dark" to squeeze through the Strait of Hormuz [2]. This narrow waterway, located between Oman and Iran, is one of the world's most critical oil transit points. According to analyst data, about two-thirds of all outbound oil tankers [2] employed these shadow-fleet tactics during the month of May.

President Donald Trump disclosed the clandestine operation in early June, saying that the U.S. secretly moved more than 100 million barrels of oil [3] to the international market. The move was designed to avoid detection by Iran, which has frequently threatened to disrupt shipping in the region.

However, the nature of the operation has been disputed. A U.S. military official said the announcement by the president referred to a previously reported effort, suggesting the operation was not entirely secret [4].

The use of a dark fleet involves disabling Automatic Identification Systems (AIS) on vessels, making them invisible to standard tracking software. This allows tankers to move through contested waters without alerting regional adversaries to the volume, or destination, of the cargo.

“Nearly 900 outbound tankers went 'dark' to squeeze through the Strait of Hormuz.”

The deployment of a state-sponsored shadow fleet represents a shift in maritime strategy, mirroring tactics often used by sanctioned nations to evade detection. By normalizing the use of 'dark' shipping, the U.S. is prioritizing the physical security of oil shipments over traditional transparency in international waters, potentially increasing the risk of miscalculation in the volatile Strait of Hormuz.