At least eight gas tankers carrying Iranian LPG have left the Gulf of Oman since mid-July, moving an estimated 4.1 million barrels past a US naval blockade that CENTCOM calls "ironclad," according to tracking analysis by United Against Nuclear Iran (UANI) reviewed by Reuters.

One additional tanker carrying Iranian jet fuel reached Myanmar in September, satellite imagery and analysis by maritime intelligence group SynMax show. US sanctions have targeted Myanmar's jet-fuel industry since 2023, citing military airstrikes on civilians that the United Nations says have killed thousands; Myanmar's junta denies targeting civilians.

Six of the eight gas tankers, plus the jet fuel carrier, already appear on US sanctions lists for transporting Iranian petroleum and petrochemical products, a Reuters analysis of Treasury vessel designations confirmed.

How are the cargoes getting through?

Tehran has concealed shipments among the growing volume of ship-to-ship (STS) transfers conducted by legitimate Gulf producers off Oman, four maritime-security sources who track Gulf oil movements told Reuters. Some Iranian LPG tankers transferred cargoes near the Omani coastal towns of Shinas and Sohar; others loitered in the Gulf of Oman before sailing past the US interdiction line, which CENTCOM has placed across the Gulf of Oman near the Iran-Pakistan border.

Most cargoes then proceeded to Malaysia's Eastern Outer Port Limits for further STS transfers, with China the likely final destination, UANI's analysis found.

Jemima Shelley, senior research analyst at UANI, put the leakage in context: "What we have seen passing is a handful of tankers carrying Iranian LPG, but the overwhelming majority of tankers laden with Iranian products have been redirected by US forces." She estimated the escaped LPG at 4.1 million barrels and characterized the shipments as driven "more by opportunism" than any new Iranian strategy of exporting via smaller vessels.

What does the blockade actually cover?

The US first imposed the naval blockade on Iran-related oil exports on April 13, lifted it in June after a draft understanding with Tehran, then reimposed it on July 14 when that agreement collapsed.

CENTCOM's October 13 update counts the results of the current phase: four commercial vessels disabled and 135 ships turned around by US forces in three months. Previous statements record ships turned back from Asia and some tankers seized outright. Last week Washington added sanctions on 17 vessels transporting Iranian crude, petrochemicals and petroleum products.

A US military official cautioned that a vessel's passage does not prove it evaded the blockade. Each ship is assessed individually, including a review of its papers, and some may pass for humanitarian reasons. Appearance on a sanctions list is not the sole trigger for interdiction, the official said; US forces monitor some ships without acting for operational reasons.

A Treasury spokesperson went further, questioning the tracking data itself — ships can spoof positions or use false identities when loading — and said such data "should be taken with a grain of salt." The spokesperson described Operation Economic Outcast and the blockade as "suffocating the Iranian regime."

What is the scale of the leak?

Small, by every measure in the data. Iranian crude exports fell to zero in September, according to Kpler — the first month without a shipment since the analytics firm began tracking Iran in 2013. US Treasury Secretary Scott Bessent has said the blockade prevented most Chinese purchases of Iranian oil and left Tehran unable to deliver crude to customers.

Neither the Iranian government nor Myanmar's military-backed government responded to requests for comment. The LPG and jet fuel cargoes, while a fraction of Iran's former export volumes, mark the first documented evidence of petroleum products penetrating a blockade that has otherwise shut down the country's crude trade.

Why jet fuel specifically?

Torbjorn Soltvedt, principal Middle East analyst at Verisk Maplecroft, flagged jet fuel as a rational choice for Tehran if it can slip tankers through, even in small numbers. US sanctions have grounded a growing share of Iran's civilian aircraft fleet, potentially leaving refineries with a surplus of jet fuel they cannot burn domestically.

Soltvedt also noted the pressure point: while Washington shows no sign of easing the blockade, worsening economic conditions inside Iran could push Tehran to take greater risks with future sailings.

For Gulf-Omega tanker owners, Omani STS brokers and forwarders moving petrochemical volumes through Malaysia's offshore transfer zones, the signal is twofold: US interdiction is demonstrably porous at the product level even as it zeroes out crude, and every documented leak tightens the sanctions net — the 17-vessel designation last week shows how quickly ship names move from watch lists to Treasury action.