Commercial Ships Navigate Strait of Hormuz Amid U.S. Blockade of Iranian Ports

The United States military began enforcing a blockade on Iranian ports on April 13, 2026, at 10 a.m. Eastern Time, following the breakdown of ceasefire talks between the U.S. and Iran ^[1][2]. The blockade restricts vessels from entering or exiting Iranian ports, but ships traveling between non-Iranian ports are permitted to transit the Strait of Hormuz ^[1][3].

In the first 24 hours of the blockade, six merchant vessels complied with U.S. directions to turn around and return toward Iranian ports, with no vessels successfully passing through the blockade ^[4][5]. However, at least three vessels, including two U.S.-sanctioned tankers, transited the Strait of Hormuz on the first full day of the blockade. These vessels were not heading to Iranian ports and thus were unaffected by the blockade ^[6][7].

A Malta-flagged crude oil carrier became the first vessel to head west through the Strait of Hormuz since the blockade commenced ^[8]. Additionally, U.S. warships, including the guided-missile destroyers USS Frank E. Petersen and USS Michael Murphy, transited the Strait of Hormuz on April 11, 2026, marking the first such transit by U.S. warships since the conflict began ^[9][10].

What Is Known

The U.S. Central Command announced and is enforcing the blockade, which aims to restrict Iranian port access while allowing commercial traffic through the Strait of Hormuz ^[1][3]. The blockade follows unsuccessful diplomatic efforts to reach a ceasefire ^[1].

What Remains Unclear

There are conflicting reports regarding whether any ships breached the blockade on the first day. While U.S. Central Command stated that no vessels passed through, some tracking data sources suggest multiple transits occurred ^[4][11]. Additionally, reports indicate that two ships may have passed through the blockade, but tracking data shows they departed before the U.S.-imposed deadline ^[5].