The commanding officer of 3d Marine Littoral Regiment (MLR), 3d Marine Division, and the commodore of commander, Submarine Squadron 1 (CSS 1) strengthened inter-service cooperation during a familiarization tour aboard the Virginia-class fast-attack submarine USS Vermont (SSN 792) on Aug. 14, 2025, signifying growing collaboration between U.S. Marine Corps and U.S. Navy forces in the Indo-Pacific region.
Col. Gabriel Diana, commanding officer of 3d MLR, joined Capt. Chris Hedrick, commander of CSS 1, for a tour of the Vermont at Joint Base Pearl Harbor-Hickam. The visit emphasized 3d MLR’s commitment to interoperability and modernization in support of the joint force by fostering relationships with naval commands.
“This partnership between 3d MLR and Submarine Squadron One represents the kind of joint force cooperation we need to maintain maritime superiority in the Indo-Pacific,” said Col. Diana. “Understanding how our submarine force operates allows us to better integrate our littoral capabilities with the broader naval campaign.”
3d MLR, redesignated from 3d Marine Regiment in March 2022, represents a fundamental shift in Marine Corps operations. Designed as a multi-domain force optimized for distributed operations across island chains, the regiment stands to disrupt the adversary through reconnaissance, counter-reconnaissance, and sea denial operations in contested littoral environments, making collaboration with submarine forces particularly valuable.
Lt. Col. David Rooks, the 3d MLR operations officer, emphasized the value of cross-service engagement. “The strategic environment in the Indo-Pacific benefits from strong relationships between all our commands,” Rooks explained. “Face-to-face interactions like this help us understand each other’s missions, share lessons, and build the trust essential for effective joint operations.”
During the tour, Vermont’s crew provided insights into submarine operations. The discussions centered on building relationships and fostering mutual understanding between the two commands operating in the same strategic theater.
“This visit allows our staff to better understand our Navy partners and the critical role they play in maintaining maritime security,” said Col. Diana. “Building these personal and professional relationships strengthens our entire joint force.”
The visit between 3d MLR and CSS 1 reflects the evolving nature of military operations in the maritime domain, where traditional service boundaries increasingly blur in favor of integrated, multi-domain operations.
“This is just the beginning,” concluded Col. Diana. “The Indo-Pacific environment demands this kind of innovation in how we work together, and partnerships like this make our entire force more capable and more lethal.”
3d MLR is a dedicated U.S. Marine Corps unit specializing in amphibious and littoral warfare operations. Stationed on Marine Corps Base Kaneohe Bay, Hawaii, and deployed throughout the Indo-Pacific region, 3d MLR is committed to promoting regional security and stability through strategic partnerships and collaborative efforts with the joint force and allied and partnered nations. Vermont is assigned to CSS 1 and is capable of supporting various missions, including anti-submarine warfare, anti-surface ship warfare, strike warfare, special operations forces support, and intelligence, surveillance, and reconnaissance.
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