The U.S. Naval Blockade is Working and Effective — FAQs and Key Facts

(New York, NY) – United Against Nuclear Iran (UANI) Chairman Governor Jeb Bush and CEO Ambassador Mark D. Wallace released the following statement and accompanying FAQs and fact sheet on the U.S. naval blockade against Iran’s regime.

“We commend President Trump for ordering the continued blockade of Iranian ports and the U.S. Navy for its highly professional and highly effective, but yet prudently selective, use of force against key Iranian shipping interests. The confusion in media reports constitutes a misunderstanding of the naval blockade.”

Some reports suggest that a U.S. blockade of Iranian-linked shipping is ineffective because certain vessels have passed through the area. These accounts may not reflect the full scope or intent of the operation. On April 22, by way of illustration, CENTCOM noted inaccurate reporting concerning three vessels, in particular, clarifying that among other claims, "Hero II and Hedy did not sail past the blockade as part of a flotilla that “ferried” millions of barrels of oil to the market [and in fact…] are anchored in Chah Bahar, Iran, after being intercepted by U.S. forces earlier this week."

The following provides clarification on current conditions.
 

When did the U.S. blockade commence?

President Trump announced the naval blockade of Iranian ports and coastal areas on April 12, 2026, after ceasefire talks with Iran ended without agreement. It took effect April 13, with U.S. Central Command confirming on April 14 that forces were "executing the mission to blockade ships entering and departing Iranian ports."

What is the blockade's rationale?

By targeting vessels calling on Iranian ports—including tankers carrying Iranian oil—the administration aims to cut off the regime's primary revenue source from crude exports, primarily to China. This applies critical pressure on the regime to open the Strait of Hormuz to international shipping and return to ceasefire talks.

How many vessels have been blocked so far?

U.S. Central Command reports at least 29 vessels turned around or back to port, with several VLCCs abandoning Iranian port calls. These successes demonstrate early deterrence against major sanctions-evading shipments.

Has the U.S. blockade failed because Iran-linked vessels are still moving?

No. This claim is based on a fundamental misunderstanding of what the blockade is designed to do.

Under the U.S. Commander’s Handbook on the Law of Naval Operations (NWP 1-14M), a blockade is "a belligerent operation to prevent vessels and/or aircraft of all nations, enemy as well as neutral, from entering or exiting specified ports, airfields, or coastal areas belonging to, occupied by, or under the control of an enemy."

The U.S. is not attempting to interdict every vessel with any connection to Iran. Rather, enforcement efforts are focused on:

• Vessels entering or departing Iranian ports; and
• Ships engaged in the transport of declared contraband cargos, as well as U.S. sanctioned Iranian cargoes, particularly crude oil and petroleum products.

As a result, the mere fact that “Iran-linked” vessels are still transiting international waters is not evidence of failure—it reflects the reality that many such vessels are not engaged in activity covered by the blockade.

Are all of the reported vessels carrying Iranian oil?

No. While some of these vessels may be transporting Iranian-origin cargoes, the majority are likely not. UANI has observed vessels departing the Persian Gulf carrying oil products from other countries—in some cases, the origin of their cargoes remains unknown.

“Iran-linked” is an expansive and vague classification. It can include vessels with historical ties to Iranian entities, opaque ownership structures, or prior sanctionable behavior—but that does not mean they are currently engaged in illicit trade.

This distinction is critical. Enforcement actions are based on present activity, not historical association.

Why isn’t the U.S. interdicting every suspicious vessel?

Because enforcement is governed by strategic and operational realities.

U.S. naval forces must weigh risk versus reward in each case. This means prioritizing:

• High-volume shipments of Iranian crude oil, particularly those destined for China;
• Large tankers (e.g., VLCCs) whose cargoes – of approximately 2 million barrels – represent significant sanctions evasion.

By contrast, interdicting a Handymax—which most of the vessels to pass were—carrying Liquefied Petroleum Gas (LPG) or marginal oil cargo (at less than 300,000 barrels) presents:

• Lower strategic impact; and
• Higher proportional risk, particularly if the use of force would be required on a high-risk LPG tanker.

In short, not every vessel is worth the escalation risk.

What about suspicious vessels that have passed through the blockade?

Due to the U.S. Navy’s global reach and long pursuit capabilities, vessels may not necessarily be interdicted at or even near the formal blockade line in the Gulf of Oman. Indeed, there have been several instances where vessels have been tracked and intercepted several thousand miles away, including the recent boarding and interdiction operation of M/T Tifani on April 21 in the U.S. Indo-Pacific Command (INDOPACOM) area of responsibility, between Sri Lanka and Indonesia. A similar operation occurred in January 2026, when U.S. forces seized a Venezuela-linked vessel, Marinera, following a 1,000 mile pursuit.

What does this mean for assessing the blockade’s effectiveness?

Effectiveness should not be measured by the total number of Iran-linked vessels at sea, but by whether the U.S. is:

• Disrupting high-value Iranian oil exports;
• Increasing the cost and complexity of sanctions evasion; and
• Deterring large-scale illicit shipments.

On these metrics, selective and targeted enforcement can be far more impactful than indiscriminate interdiction.

We will be able to assess this more clearly by tracking whether these tankers appear— or fail to appear—at key chokepoints like the Malacca Strait, where their movements can be verified through satellite imagery and AIS data. This is ultimately the more meaningful measure of effectiveness.