CAMP SHIELDS, OKINAWA, Japan - Just off the coast of Okinawa, Japan, in the East China Sea, Seabees assigned to Naval Mobile Construction Battalion (NMCB) 4 and Marines with 3d Marine Logistics Group and 1st Marine Air Wing rehearsed the establishment of an Expeditionary Advanced Base (EAB) as part of exercise Poseidon’s Watchtower, June 2-17, 2021, on the islands of Ukibaru and Irisuna, Okinawa, Japan.

In a unified effort with 3d Landing Support Battalion, Marine Heavy Helicopter Squadron (HMH) 462 and Naval Beach Unit 7, NMCB-4 and 9th Engineer Support Battalion (ESB) delivered both troops and supplies to establish an EAB on remote islands off the coast of Okinawa. Naval Construction Forces and other Navy Expeditionary Combat Command units like NMCB-4 execute Expeditionary Advanced Base Operations (EABO) in order to support and protect the fleet through Distributed Maritime Operations.

“It’s all about expeditionary logistics and supporting the fleet from the littorals so that they can achieve sea control,” said Lt Cmdr. Steven Bischak, Poseidon’s Watchtower Exercise coordinator. “This exercise has been really unique in the aspect of getting and sustaining forces on the islands. We really had to come through with the amphibious forces from CTF 76, who transported us on USS New Orleans and off-loading equipment on Landing Craft Air Cushions, then utilizing the power of HMH 462 and its CH-53E Super Stallion Helicopters. This exercise really showed how Seabees can take advantage and exploit key maritime terrain using the sea lift and air lift in order to get the mobility we need to get on target.”

Through the exercise, NMCB-4 showcased naval integration with multiple units such as 3d Landing Support Battalion, Underwater Construction Team Two, 9th ESB, and HMH 462, whilst spread out between two remote islands, Ukibaru and Irisuna. On Ukibaru, Sailors and Marines conducted a land and water engineering reconnaissance of key maritime terrain. With the support of 3d MLG Intelligence and emerging Light Detection and Ranging (LiDAR) technologies, the naval engineering team developed an integrated assessment of the island’s ability to serve as a location for High Mobility Artillery Rocket System (HIMARS) and maritime refueling. The Navy-Marine Corps team collected and transferred data to the Construction Operations Integration Center (COIC) on Camp Shields that developed designs for Littoral Transition Points to rearm, resupply, and refuel future naval platforms such as the Light Amphibious Warship (LAW) and Extra Large Unmanned Undersea Vehicle (XLUUV).

On the other side of Okinawa, atop a weapons training range on Irisuna Island, Seabees and Marines exercised the ability to live and operate in austere conditions within the weapons engagement zone. The Navy-Marine Corps team built a concrete bunker with locally sourced low-signature materials, demonstrating how the Seabees can construct infrastructure specific to warfighting capabilities anywhere in the world.

"We showed the ability of expeditionary bases, specifically in this case, as we’re able to put bunkers in different locations,” says Builder 1st Class Nathaniel Mitchell, Assistant Officer in Charge and project site manager for Poseidon’s Watchtower on Irisuna. “The biggest take away is the fact that we can get pushed forward, deployed anywhere, and still take care of business when we need to.”

Poseidon’s Watchtower was a pioneering exercise for the Seabees and Marines as it showcased the maritime services’ ability to meet expeditionary needs, especially in remote locations in the 7th Fleet area of responsibility.

NMCB-4, based out of Port Hueneme, California, is forward-deployed throughout the Indo-Pacific region ready to deliver engineering solutions and construction of expeditionary and advanced naval base facilities to Naval and Joint Force Commanders.

Photo Caption: Equipment Operator Constructionman Brent Wielms, assigned to Naval Mobile Construction Battalion (NMCB) 4, operates a skid steer to relocate building materials from beach side to a project site on W-174 Joint Okinawa Training Range Complex, an uninhabited island off the coast of Okinawa, Japan, as part of joint exercise Poseidon’s Watchtower. Poseidon’s Watchtower is a multi-domain exercise designed to simulate the establishment of Expeditionary Advanced Base operations through joint service integration.