The United States has introduced restrictions on the timing of military-protected transit for commercial tankers passing through the Strait of Hormuz, following an increase in Iranian attacks on vessels navigating the route at night. Since May, Washington has provided air defence coverage to ships traveling along a southern path near the Omani coast, aiming to secure oil shipments from the Gulf amid heightened regional tensions.
Under the program, ship operators were required to coordinate with the US Naval Cooperation and Guidance for Shipping (NCAGS) center to receive specific coordinates and approval for overnight transit during broad windows when US aircraft were on patrol. However, beginning in early September, NCAGS reduced these periods to two narrowly defined daily time slots, asking vessels to commence their passage at designated hours, such as 9 a.m.
Communications from NCAGS encouraged, but did not mandate, adherence to these recommended times, noting that transiting during darkness had proven less secure due to increased threats. US Central Command declined further comment beyond affirming the authenticity of the NCAGS messages.
The adjustment coincides with escalating attacks on commercial vessels by Iranian forces. More than 70 merchant ships have reportedly been targeted since the conflict escalated on February 28. The Islamic Revolutionary Guard Corps (IRGC) is known to deploy small patrol boats actively monitoring shipping routes, especially vessels moving at night without operating GPS or lights.
Experts note that the US shift toward restricting transit times aims to balance resource allocation with the need to maintain effective defence coverage. Naval analyst Joshua Tallis of CNA, a US security research organization, described the measure as a cost-effective approach to managing the significant expenses associated with continuous military air patrols, which can range from $25,000 to $75,000 per flight hour. By focusing defence efforts within limited windows rather than maintaining a 12-hour overnight presence, the US can concentrate military assets and ensure stronger protection during those periods.
A maritime security adviser working with Gulf shipping operations echoed this view, suggesting that the compressed transit schedule allows for optimal use of US military capabilities. Retired Vice Admiral John Miller, former commander of US naval forces in the Middle East, added that sustaining 24/7 air cover indefinitely would be challenging, necessitating guidelines to preserve assets and maintain ongoing security.
Commercial vessels typically require about seven hours to navigate the strait at moderate speeds. The US measures indicate an ongoing effort to safeguard maritime traffic while adapting to the evolving security landscape in this strategically vital corridor.