MASGA Shows that the US-South Korea Defence Relationship Has Changed

The U.S.-South Korea defence relationship, which for decades was characterized by the heavy dependance of the Asian nation on Washington for weapons and military assistance, is no longer a one-way street.

With the U.S. seeking to expand its maritime power to keep pace with China that leads globally when it comes to shipbuilding capabilities, Washington is turning to South Korea, which is second only to China when it comes to shipbuilding capabilities. A major step in this direction is “Make American Shipbuilding Great Again” (MASGA), a strategic partnership agreed upon in August this year by U.S. President Donald Trump and South Korean President Lee Jae Myung.

Seoul’s emergence as a major shipbuilding power comes at a time when the U.S. Navy has struggled with delays to many key shipbuilding programs as well as maintenance of existing ships. MASGA taps heavily into Korean expertise in shipbuilding. Under the initiative, South Korea has committed to investing US$150b to improve commercial and military shipbuilding production capacity in American shipyards; its shipbuilding companies will also provide workforce training and naval maintenance, repair and overhaul (MRO).

Notably, MASGA also envisages the U.S. purchasing ships made by Korean companies. Protectionist American legislation, which prohibits the manufacture of US Navy warships in other counties as well as the use of non-US-built vessels to transfer goods across American ports, might act as a dampener, but analysts expect Washington and Seoul to find a way around it.

The U.S. currently only accounts for 0.04% of global shipbuilding output. Seoul sees MASGA as chance to not only provide Pentagon with the help it needs in the sector but also to grow the global market share of its domestic companies. As part of the initiative, as many as 11 non-binding shipbuilding industrial agreements have been signed between companies in the two countries. Hanwha, Samsung and HD Hyundai Heavy Industries are among the Korean companies that will benefit from the partnership.

A Real Gamechanger

At September’s Korea Investment Week 2025 (KIW 2025) forum in Seoul, representatives of Korean companies outlined plans to make MASGA a reality.

Hanwha Ocean intends to create a Korean MRO hub for US naval vessels in Busan and the surrounding South Gyeongsang Province, besides transforming Philadelphia-based Hanwha Philly Shipyard Co. into a production base in the U.S. Hanwha acquired the shipyard in 2024. The company is expected to expand its U.S. presence by partnering with smaller Korean shipbuilding equipment makers.

“By leveraging more than 1,000 suppliers in Busan and its surrounding area, we aim to create a specialized cluster capable of handling MRO for 11 US Navy vessels annually,” Choi Jeong-hoon, head of special ship planning at Hanwha, said, The company will invest US$5 billion and enhance Philly Shipyard’s capacity from the current little more than one vessel a year to 20, he added.

In partnership with American Huntington Ingalls and Edison Chouest Offshore, HD Hyundai has plans to provide marine logistics infrastructure and advanced technological equipment to the US shipbuilding industry, The company recently reopened a dormant shipbuilding facility in Subic Bay in the Philippines. This facility is being developed into an MRO hub for a variety of vessels, including frigates and patrol craft.

HD Hyundai’s recent merger of its shipbuilding operations will also see more U.S. Navy warships produced, says Jang Gwang-pil, vice president of HD Korea Shipbuilding & Offshore Engineering Co. ″There is a high possibility that HD Hyundai Heavy’s special ship division will work with HD Hyundai Mipo to build warships, including the Aegis destroyer.”
Samsung Heavy Industries signed an agreement in August this year with Oregon-based Vigor Marine Group to modernize US Navy support facilities, co-develop vessels and share MRO work. “The partnership will extend to co-building commercial and naval ships, and to investing heavily in workforce training in the US,” said Lee Ho-gi, a Samsung Heavy executive.

Growing Partnership

In April this year, HII, the largest naval shipbuilder in the U.S., and South Korean shipbuilder Hyundai Heavy Industries signed a memorandum of understanding “to explore opportunities to collaborate on accelerating ship production in support of defense and commercial shipbuilding projects.”

In August, Hyundai Heavy Industries won a maintenance, repair, and overhaul (MRO) contract for the US Navy Lewis and Clark-class dry cargo ship USNS Alan Shepard. The work includes propeller cleaning, tank maintenance, and inspections of onboard equipment. In March, Hanwha Ocean became the first South Korean yard to bid on and win a regular overhaul contract of an US Navy vessel; the company successfully completed its work on the USNS Wally Schirra, another Lewis and Clark-class dry cargo ship.

A Boon for Both Sides

“Increased South Korean defense industrial base capacity, particularly in arms and shipbuilding, has the potential to directly support the United States,” says a 2024 report from the DC-based Stimson Center. “…increased cooperation with South Korea—a global leader in shipbuilding—presents a critical opportunity to reduce U.S. dependency on Chinese commercial ships and components while fulfilling core economic and security needs, particularly as U.S. shipbuilding programs face delays. This cooperation could be as minor as increasing the use of South Korean parts in U.S. shipbuilding or as extensive as coproduction,” the report adds.

Buoyed by the growth of its domestic defence industry and the key role it is expected to play in improving U.S. shipbuilding capabilities, Seoul is working to restore the balance of the partnership. In August this year, the Lee Jae Myung administration confirmed in its five-year policy road map that it would seek to reclaim wartime operational control (OPCON) of the military from the U.S. within the next five years. Previous administrations had unsuccessfully tried to complete OPCON transfer.

Viable Alternative

Due to its long-standing ties with the U.S. in the defence sphere, South Korea’s defense industry has focused on the need for interoperability while developing weapons. This makes weapons made by South Korean companies an attractive option for NATO countries and other militaries that are looking beyond Washington for their defence needs.

South Korea exported $121 million in weapons to the U.S. in 2023, according to the Observatory of Economic Complexity; Poland was the only country that imported more Korean arms that year. In November 2022, the U.S. decided to buy 100,000 rounds of howitzer artillery from South Korean manufacturers to help Ukraine thwart Russian aggression. In April 2023, South Korean media reported that the country would instead lend the United States 300,000 rounds of 155mm artillery shells.

Still Tilted One Way

Korean companies are seeing increasing success in growing their U.S. footprint, but Seoul still imports far more U.S. made weapons than it sells to Washington. In April 2024, South Korean military procurement agency Defense Acquisition Program Administration (DAPA) approved the purchase of Raytheon-made SM-3 missiles. The SM-3s will be installed on Aegis ships and purchased through the US Foreign Military Sales program. The project costs about US$583 million.

In September 2023, the United States approved a US$5 billion sale to South Korea of 25 Lockheed Martin F-35 jets as well as engines and related equipment. South Korea has operated the fifth-generation fighter jet since 2018. Seoul’s days of near-total reliance on the U.S. for weapons are long over, but industry analysts expect the U.S. to continue providing the Asian nation specialized weapons.