91 Iran-Linked Tankers in Limbo as US Blockade Roils Energy Markets

For climate and energy analysts, the disruption of Iranian exports—which include LPG and petrochemicals—could have a double-edged effect. Higher fossil fuel prices incentivize renewables, but short-term supply shortages may trigger a scramble for dirtier alternatives like coal, amplifying emissions at a critical juncture in the energy transition.

In a dramatic escalation of US-led maritime enforcement, two US-sanctioned liquefied petroleum gas (LPG) carriers—Glendale and Danuta I—began executing abrupt U-turns and erratic zig-zag patterns in the Gulf of Oman and Arabian Sea on July 16–17, 2026. Their behavior is the most visible manifestation of a renewed and aggressive blockade that the United States launched on July 14, aiming to cripple Iranian energy exports. US Central Command (CENTCOM) confirmed that since the operation began, American forces have redirected three merchant ships, boarded one for verification, and disabled a tanker with missiles deep in the Persian Gulf near Iran’s Kharg Island oil terminal. These actions, combined with satellite data showing 91 Iran-linked tankers—including empty ones—loitering in the region, signal a significant widening of the operational theater compared with previous blockade efforts. The boarding in the Gulf of Oman and the missile strike near Kharg Island suggest that the US is now interdicting vessels across the full length of Iran’s coastal waters, effectively sealing off the Strait of Hormuz approach.

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The three named tankers—Glendale, Danuta I, and the very large gas carrier Celeste—had been signaling destinations in Sri Lanka and China, but their real voyages are now in chaos.

The immediate context is the reinstatement of a “maximum pressure” campaign by Washington, likely driven by stalled nuclear negotiations and Tehran’s continued military support for regional proxies. Historically, US naval operations against Iranian shipping have oscillated between covert interdictions and explicit military action. The current cycle, however, appears more kinetic: disabling a tanker with missiles marks a qualitative leap from past tactics of simply seizing cargo or detaining vessels. This direct use of force within Iranian territorial waters or the contiguous zone raises the risk of a military confrontation, especially if Iran’s Islamic Revolutionary Guard Corps Navy (IRGCN) retaliates with fast-attack craft or mines.

For global energy markets, the disruption is immediate and tangible. Iran is a major exporter of LPG and crude oil, much of which flows to China through opaque, sanctioned trade networks. The three named tankers—Glendale, Danuta I, and the very large gas carrier Celeste—had been signaling destinations in Sri Lanka and China, but their real voyages are now in chaos. Shipping data reveals Glendale abruptly halted off Oman after a U-turn, while Danuta I slowed to a crawl and abandoned its course toward Sri Lanka. Celeste continues into the Arabian Sea, still indicating China, but its ability to discharge cargo is now uncertain. With 91 tankers counted by the nonprofit United Against Nuclear Iran over a seven-day period, the sheer volume of idle or at-risk tonnage points to a substantial portion of Iran’s export fleet being effectively blockaded. This includes ballast vessels, suggesting that even returning empty ships face inspection or worse, throttling the logistical cycle.