The U.S. blockade tied to Iranian ports is now underway, but after its first day, it does not resemble a full naval shutdown of the Strait of Hormuz. Early signals point to reduced traffic, uneven enforcement and continued Iranian leverage over a waterway that remains tense and only partly open.
The Wall Street Journal reports the U.S. has positioned more than 15 warships for the operation. Ship-tracking data cited by CNN and BBC Verify shows light traffic near Iranian ports and a sharp drop in overall flow— but not a total halt.
Why the blockade falls short of full control
The U.S. is trying to squeeze Iran economically by blocking traffic tied to its ports, not by closing the Strait entirely. But Iran still holds a key advantage: geography.
PHOTO OF THE DAY: Fog of war over Kharg Island (literally).
Iran was loading two oil tankers on Saturday (April 11th) as seen on this @CopernicusEU Sentinel 2
satellite picture. Another tanker is seen near the jetty, plus another two are on the nearby anchorage. pic.twitter.com/U522TON4TV
— Javier Blas (@JavierBlas) April 13, 2026
The Washington Post reports that the Strait’s narrow lanes, shallow waters, islands and elevated coastline make ships highly exposed to mines, missiles, drones and small-boat attacks. That means the real deterrent is not simply the U.S. Navy’s presence. It is the continued risk of crossing at all.
Before the war, more than 130 ships crossed the Strait daily, according to Kpler data cited by The Post. Since the ceasefire, that average has fallen to about seven a day. More than 700 vessels remain in the Gulf, according to Windward data.
How the US is enforcing the blockade
The Journal reports the U.S. is likely trying to intercept or quarantine vessels outside the Persian Gulf, in areas like the Arabian Sea, rather than crowd warships near Iran’s coastline. That approach reduces the danger from Iranian attacks while still targeting ships linked to Iranian commerce.
If a ship’s crew refuses to comply, enforcement would require specialized tactical units, like Marines or Navy SEALs, to board vessels. Former officials also told the Journal that if the U.S. actually takes control of tankers, it may need replacement crews and designated places to hold them.
The Journal also reports Iranian-flagged ships may still attempt to pass through the Strait, potentially with armed escorts from the Islamic Revolutionary Guard Corps.
CNN’s reporting suggests enforcement remains uneven and difficult. Windward analysts say outbound traffic may be easier to control than inbound vessels, especially when ships use deceptive tracking practices.
A shipping executive told CNN the blockade should not be taken too literally.
“I would be careful not to interpret that too literally as a physical interdiction at the Strait itself,” said Bjorn Hojgaard, CEO of Anglo-Eastern.
What ship-tracking data shows so far
So far, shipping data shows both pressure and gaps in enforcement. CNN reports limited movement in and out of Iranian ports during the first full day, but says some tankers are still transiting the Strait.
BBC Verify reports at least four Iran-linked ships crossed after the blockade began, including vessels tied to Iranian ports or already under U.S. sanctions. Some ship positions may also be masked through spoofing. That mixed picture helps explain continued caution across the shipping industry. . The Post reports Hapag-Lloyd is still avoiding the Strait under its current risk assessment. Analysts told the paper traffic is unlikely to rebound quickly unless operators believe the ceasefire will hold and the threat to vessels will ease.
CNN also reports the broader dispute remains unresolved. Iran continues to link full access to the Strait to a wider agreement over its nuclear program, sanctions, security guarantees and other terms, while the U.S. is demanding the immediate reopening of the waterway.