The discourse on US-Japan shipbuilding cooperation materialized in earnest in April 2025, prompted by US Secretary of the Navy John Phelan’s proposal during interviews with Japanese media. The interview highlighted the manufacturing of commercial vessels convertible for military use and Japanese investments in the US West Coast shipbuilding industry. Prior to his visit to South Korea on April 30, Secretary Phelan visited the Japanese Ministry of Defense and local shipyards on April 28 to discuss defense and shipbuilding industry cooperation.1) Subsequently, through several rounds of US-Japan tariff negotiations conducted between April and July, the two nations solidified their commitment to cooperation in strategic sectors, including shipbuilding, based on the “Manufacturing Renaissance Partnership.” This led to the gradual specification of cooperative measures, culminating in the signing of a Memorandum of Cooperation (MOC) in the shipbuilding sector on October 28.