COSCO Breaks the Hormuz Blockade. Only China Gets Through.

A COSCO container ship completed a full transit of the Strait of Hormuz on Monday, the first commercial vessel to pass through the chokepoint since US-Iran hostilities closed it to most traffic in early March.

The transit, confirmed by shipping tracking data and multiple port authorities, took place without military escort from the US Fifth Fleet. COSCO, China's state-owned shipping giant, coordinated directly with Iranian naval authorities to secure passage, according to three people familiar with the arrangement cited by Reuters.

No Western-flagged vessel has attempted the crossing since March 5.

Two Straits, Two Systems

The successful passage creates what analysts are calling a bifurcated shipping system — one lane open to Chinese-affiliated vessels, another closed to everyone else.

"This isn't just a ship going through a strait," said Greg Poling, director of the Asia Maritime Transparency Initiative at CSIS. "This is China establishing a parallel trade infrastructure in real time."

China imports roughly 10 million barrels of oil per day, with about 40% transiting Hormuz before the war. While those flows dropped sharply in March, the COSCO transit signals Beijing's intent to restore them on its own terms.

Iranian state media celebrated the passage. Press TV called it "proof that the Strait of Hormuz remains open to nations that respect Iran's sovereignty." IRIB described it as a "strategic partnership corridor."

The Price of Exclusion

For nations without Beijing's direct line to Tehran, the strait remains effectively sealed. Japan, South Korea, India, and most of Europe continue rerouting oil shipments around the Cape of Good Hope, adding 10 to 14 days and roughly $3 to $5 per barrel in transport costs, according to Clarksons Research.

South Korea's Ministry of Trade said Monday it was "closely monitoring" the COSCO transit. A spokesperson declined to say whether Seoul had sought similar arrangements with Tehran.

Japan's Chief Cabinet Secretary Yoshimasa Hayashi said Tokyo was "gathering information" but offered no indication that Japanese-flagged vessels would attempt the crossing.

India, which has historically maintained its own back-channel relationships with Tehran, has deployed naval warships to escort its tankers through the strait, according to Hindi-language reporting from News18 Hindi. That operation has received almost no coverage in English-language media.

What Beijing Gets

The arrangement gives China several advantages beyond cheaper oil. It positions Beijing as the indispensable intermediary for any nation wanting Gulf access, strengthens China's leverage over Iran's war economy, and demonstrates that US naval dominance does not translate into trade dominance when an adversary controls the shore.

China purchased roughly 90% of Iran's oil exports in March, according to Kpler tanker-tracking data. Those purchases came at narrowing discounts — Iran sold at just $4 to $6 below Brent, compared with discounts of $12 to $15 before the war.

"Iran is earning more per barrel now than it did at peace," said Samir Madani, co-founder of TankerTrackers.com. "The war that was supposed to cripple its economy is funding it."

The Precedent Problem

International shipping law treats straits like Hormuz as transit passages open to all vessels under the UN Convention on the Law of the Sea. Iran's selective enforcement — allowing Chinese ships while blocking or threatening others — challenges that framework directly.

The US State Department said it was "aware of reports" of the COSCO transit but did not address whether Washington views selective strait access as a violation of international law.

Lloyd's of London has not updated its war-risk insurance premiums for Chinese-flagged vessels transiting Hormuz. Premiums for all other flags remain at record levels, effectively adding 2% to 3% of hull value per transit.

The next test comes within days. Shipping intelligence firm Windward identified at least three more Chinese-affiliated vessels approaching the strait from the Indian Ocean as of Monday evening. Whether they transit successfully will determine if this was a one-off or the beginning of a permanent corridor.