U.S. Navy Tests Amphibious Assault Ship Strait Transit as Chokepoint Threats Intensify.

U.S. Navy and Marine Corps forces aboard USS Boxer conducted a simulated strait transit in the Pacific, training for operations in confined and threat-dense waters. The drill reflects growing concern that routine chokepoint transits could rapidly turn contested in a future crisis.

Released on January 27, 2026, new imagery and unit reporting show Marines and Sailors of the Boxer Amphibious Ready Group and the embarked 11th Marine Expeditionary Unit running a simulated strait transit aboard the Wasp-class amphibious assault ship USS Boxer (LHD 4) in the Pacific. The event was framed as a force-protection and navigation-intensive drill, but its real purpose is sharper: to rehearse how an amphibious formation fights, maneuvers, and maintains command and control when sea room disappears and threats can emerge from both coastlines with little warning. For the Navy-Marine Corps team, this is not a niche evolution but a recurring operational reality, where routine passage through chokepoints can rapidly become a contested transit with high political and tactical stakes.
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Marines and Sailors of the Boxer Amphibious Ready Group and 11th Marine Expeditionary Unit conduct a simulated strait transit aboard USS Boxer (LHD 4), rehearsing tight-formation navigation and layered shipboard defenses for chokepoint operations. The drill stresses rapid contact identification, counter-drone measures, and coordinated aviation overwatch to reduce risk in confined waters where coastal threats, mines, and dense commercial traffic compress reaction time (Picture source: U.S. DoW).

Although labeled “simulated,” the problem set is real: an amphibious task force does not get to choose where geography squeezes it. The Boxer ARG’s west coast training package has been operating with San Antonio-class amphibious transport dock USS Portland (LPD 27) and Whidbey Island-class dock landing ship USS Comstock (LSD 45) in recent integrated events, giving the formation the classic three-ship amphibious toolkit: a big-deck aviation hub, a command-and-connector optimized LPD, and a well-deck workhorse built to push landing craft and vehicles.

In a strait scenario, the ships’ defensive suites matter as much as the Marines’ combat power, because the threat timeline collapses. Wasp-class LHDs carry a layered self-defense fit built around Rolling Airframe Missile launchers, NATO Sea Sparrow launchers commonly paired with Evolved Sea Sparrow Missiles, Phalanx CIWS, and multiple crew-served and medium-caliber mounts intended to defeat leakers and fast inshore attack craft at close range. Portland, as an LPD, adds its own point-defense mix, including RAM and 30 mm guns, and is designed to keep moving Marines, vehicles, and landing craft while still fighting the ship. Comstock’s armament similarly reflects the amphibious reality: CIWS and RAM for last-ditch missile and drone defense, Mk 38 guns and machine guns for swarm threats, all while operating a well deck that can become a signature and a vulnerability in confined waters.

The 11th MEU’s aviation and ground elements are what turn a tense transit into an armed passage with options. Recent imagery tied to the MEU’s workups shows an F-35B Lightning II operating from Boxer, with the jet’s value in this context extending beyond strike to sensor-driven early warning and cueing for the task force, especially when the air picture is cluttered by coastal terrain and dense civilian traffic. In parallel, the MEU’s tiltrotor component provides the reach to launch and recover visit-board-search-and-seizure teams, reposition air defense detachments, or push small reconnaissance elements to key coastal vantage points if the scenario demands it, while heavy-lift sorties support rapid movement of bulk equipment that would otherwise be trapped in the sea lane.

One of the most telling details in strait drills today is the counter-uncrewed aircraft layer. The Marine Corps has been explicit that systems like the Light Marine Air Defense Integrated System are built to bring electronic attack and detection into expeditionary spaces, including shipboard employment, where a small drone can be both a targeting node and a munition. LMADIS’ utility in a transit is not cinematic shoot-down footage but the quieter effect of breaking the kill chain: disrupting control links, forcing an adversary to burn sensors, and buying seconds for the ship’s own hard-kill systems and tactical maneuver.

A strait transit is a compression of naval warfare into a corridor. The force must maintain station in restricted water, manage deconfliction with commercial shipping, and still present a coherent defense with overlapping sectors. That usually means tighter rules on emissions control and radar use, deliberate positioning of helicopters to extend the surface search and identify contacts early, and aggressive topside posture with stabilized guns and ready magazines. It also means constant coordination between the amphibious squadron’s watch teams and embarked Marines, because in a littoral fight the contact might be a fishing dhow, a fast skiff, a low-flying quadcopter, or a missile boat running in the land clutter, and the time to classify is measured in breaths.

The danger is structural: in deep ocean, threats tend to arrive from fewer directions with more warning and more maneuver room. In a strait, coasts on both sides create overlapping engagement zones for anti-ship missiles, rockets, and drones, while shallow water constrains submarine geometry and increases the mine problem. Geography also amplifies mistakes. A minor navigation error, a misunderstood radio call with a civilian vessel, or a late turn in a narrow lane can cascade into collision risk, mission delay, or a self-inflicted loss of formation integrity that an enemy would happily exploit.

That is exactly why the U.S. Navy needs to train this way, repeatedly, and with Marines fully integrated. Amphibious ready groups and carrier strike groups circulate through chokepoints as a matter of routine and strategy, from the Strait of Hormuz and Bab el-Mandeb to Indo-Pacific passages where a crisis can turn a normal transit into a contest of wills. The Navy cannot opt out of geography, and the Marine Corps cannot assume it will be delivered to an objective area unmolested. A well-rehearsed strait transit, with aviation overhead, counter-UAS measures active, and shipboard defenses drilled to muscle memory, is less about theatrics and more about reducing the probability of surprise in the one place surprise is easiest to engineer: the narrow water where everyone can see you coming.

Written by Evan Lerouvillois, Defense Analyst.

Evan studied International Relations, and quickly specialized in defense and security. He is particularly interested in the influence of the defense sector on global geopolitics, and analyzes how technological innovations in defense, arms export contracts, and military strategies influence the international geopolitical scene.