In August 2026, the White House released a shipbuilding memorandum to “restore both capacity and competition” of the US maritime industrial base. Section 3 of the memo directed the Secretary of War to submit a plan to explore partnering with allies to build and deliver foreign-designed ships through the “Finland Model”—a framework that seeks to gradually bolster domestic shipbuilding capacity through ally cooperation. (This is based on a US Coast Guard agreement for Finland to build the first two Arctic Security Cutter icebreakers, while production of later cutters transfers to a US shipyard.) A month later, USNI News reported that Washington was considering frigate designs from Japan, South Korea, and Türkiye, and Acting Secretary of the Navy Hung Cao directed a study of international combatant ships.
In anticipation of the November deadline for the Department of War’s review, we offer a basic overview of two of the more likely ships for US Navy use: the Japanese Mogami-class and South Korean Chungnam-class frigates. We compare their relative strengths and weaknesses in terms of capabilities, acquisition timelines, and potential for interoperability with other US Navy assets. The ultimate decision may come down to weighing trade-offs between the capabilities and interoperability of the one against the potential speed of delivery of the other.
Capabilities
The large Japanese Mogami-class frigate has a standard displacement of 4,880 tons and reaches over 30 knots. It has anti-submarine, anti-surface, and anti-air capabilities. The Mogami-class automation helps reduce crew size, down to 90 sailors in contrast with 200 on Japanese destroyers—and over 300 on US destroyers. Automation can also reduce bridge manning to as low as four or five sailors under certain conditions. This feature is desirable given persistent US Navy shortages of sailors at sea. Its vertical launch system (VLS) has 32 missile cells.
In comparison, South Korea’s smaller Chungnam-class frigate displaces 3,500 tons. It is equipped with 16 vertical launch system cells for anti-ship and long-range anti-submarine missiles and has a “semi-Aegis” system for integrated fire control.
| Weapons |
|
|
|---|---|---|
 |
32-cell vertical launching system with:
11-cell SeaRAM Close-In Weapon System 2 quad launchers with Naval Strike Missile. |
16-cell Korean vertical launching system with:
2 quad launchers with Haeseong I anti-ship cruise missiles |
 |
2 triple-tube launchers for Mark 54 torpedo | 2 triple-tube launchers for K745 Blue Shark torpedo |
 |
Mark 45 127mm gun |
Mark 45 127mm gun Close-In Weapon System II with 30mm gatling gun |
 |
1 SH-60 Seahawk helicopter USV/UUV ramp and mission bay |
1 Mk99 Lynx or 1 AW159 Wildcat helicopter |
Delivery Timeline
Speed of delivery is a relevant factor in assessing ship models. Advocates of the “Finland Model” argue that faster delivery of more ships is an appealing factor. Recently Australia contracted for a Mitsubishi Heavy Industries export variant of Japan’s Mogami-class frigate for delivery beginning in 2029. The Australian defense minister called it the Australian Navy’s quickest acquisition. In addition, the contract includes technology transfer to Australia, similar to the “Finland Model” conditions set in the White House memorandum. The total purchase will be approximately $6.5 billion for the fleet of frigates, or about $590 million per vessel.
For South Korea’s Hyundai Heavy Industries, delivery of the $300 million Chungnam-class is estimated at roughly 18 months from procurement to creation. Seoul’s deep ties in Washington may enable it to maneuver even more quickly through the design stage. For example, the jointly opened Korea-US Shipbuilding Partnership Center in Washington, DC, was established in hopes of facilitating enhanced cooperation on shipbuilding. It is possible that South Korea’s many levers and shipbuilding investments in the US may support expedited shifting from Korean to US yards for later builds, consistent with the White House memorandum requirements.
Interoperability
US Navy sailors will place the highest value on foreign designs that require the fewest modifications to accommodate Navy systems, equipment, personnel, and procedures—reducing operational barriers and bolstering interoperability. For instance, upgraded Mogami-class ships will be equipped with Naval Strike Missiles and 32 cells of the US-made Mk 41 vertical launch system (VLS), a potential advantage. In contrast, the Chungnam-class features the Korean K-VLS with only 16 missile cells. Since this launch system is currently capable of launching only Korean missiles, it would require the US to either: (1) buy Korean missiles, (2) assess modification of select US missiles for the K-VLS launcher, or (3) convert the VLS to Mk 41. Any of those options may require major verification, integration, and testing. The Mogami may have another advantage in this area, given reported plans to integrate critical US Navy missiles (such as SM-2, SM-6, and Tomahawk) into the Australian Mogami export variant.
Both ship classes use their own combat management system (CMS), rather than the Aegis combat system, which impacts their ability to command and control US missiles and combat weapons systems more broadly. The frigates’ CMS must also be able to share targeting data with US ships, preferably across a US-derived network, to enable a shared common operational picture and integrated sensor-to-shooter architecture. Both countries regularly operate Link 16 for tactical data exchange with the US, and the Mogami-class possesses the antenna within its integrated sensor mast (ISM). Despite the Chungnam-class also having a highly advanced ISM, public information is lacking on whether Link 16 is installed within its data link system.
Perhaps the hardest interoperability issue to assess is how foreign built ships will be sustained and repaired in the future. Shifting production to the United States over time is intended to mitigate this risk. The three navies share technical knowledge for some ship components that could eliminate production barriers. For instance, both frigates use the Rolls-Royce MT30 gas turbine engine, which is used by many US ships and can be serviced within the US. Japan and South Korea are capable of servicing the engine, which is beneficial if the US were to operate either frigate near those countries.
Tradeoffs for the Final Decision
As the Department of War assesses the viability of pursuing foreign-built combatants and transferring production knowledge to the US, Japanese and Korean frigates likely top the list of options, though their relative strengths differ. In terms of capability, the Mogami seems to come out on top given its larger missile capacity for key US munitions and its multi-mission performance. Looking at speed of production, the Chungnam likely has an advantage due to South Korea’s US shipbuilding investment ties and faster estimated production time, though Japan is implementing a frigate technology transfer plan with Australia right now. Therefore, interoperability may be the ultimate deciding factor, specifically how much the US Navy wants and needs to deviate from the parent design to properly integrate the ship with the rest of the fleet. For both mission effectiveness and long-term ship sustainment, potential foreign ship procurement could hinge on this critical aspect.
