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Japan and South Korea Face Off Again in the US Navy’s Frigate Search

South Korea has an industrial head start, but is Japan’s upgraded Mogami class merely a stalking horse for the Chungnam class?

Japan’s upgraded Mogami-class frigate, the New FFM (left), and South Korea’s Chungnam-class frigate

The U.S. Navy’s reported interest in foreign frigate designs has opened a new front in Japan-South Korea defense industrial competition. USNI News reported on September 1 that the White House and Navy are considering three allied designs: Japan’s upgraded Mogami class, known as the New FFM or 06FFM; South Korea’s Chungnam class; and Turkiye’s Istanbul class. Up to two ships could be built overseas before production shifts to U.S. yards.

The idea did not come from nowhere. As Naval News reported in June, the Pentagon’s fiscal year 2027 budget proposal included $1.85 billion for an effort involving foreign warship designs, with Japan and South Korea at the center of the discussion.

Japan’s top naval officer has now publicly welcomed the reported U.S. interest. Asked by The Diplomat at a September 8 press conference about the New FFM’s reported inclusion in the U.S. review, Japan Maritime Self-Defense Force (MSDF) Chief of Staff Adm. Saito Akira stressed that he was not in a position to comment on individual U.S. Navy shipbuilding plans. But if the United States or other countries were considering adopting platforms used by the MSDF, he said, “We see this as reflecting a high level of trust in and appreciation for equipment that embodies the advanced technologies of our ships.”

“I am frankly pleased,” Saito said, adding that if Japan received requests for cooperation on such matters, “we would respond proactively.” 

The reported competition has encouraged a view that Seoul is the real front-runner and Japan’s New FFM merely a stalking horse. Hanwha acquired Philly Shipyard in 2024, giving a South Korean company a direct U.S. shipbuilding foothold. U.S. officials have repeatedly visited South Korean yards, and in December 2025 U.S. President Donald Trump said the Navy would work with Hanwha on a new frigate.

But that conclusion does not necessarily follow.

Trump’s remarks referred to cooperation on the U.S. Navy’s FF(X), a U.S.-designed frigate concept based on the Coast Guard’s National Security Cutter. That was not a decision to adopt South Korea’s Chungnam design. USNI News’ September 1 report described a separate review of foreign designs and identified no favorite. 

Moreover, Hanwha is not the company most closely associated with the Chungnam class. The detailed design and lead ship were handled by HD Hyundai Heavy Industries, while Hanwha Ocean and SK Oceanplant are building follow-on ships. Thus, Hanwha’s U.S. shipyard investment does not automatically translate into an advantage for the Chungnam design.

Nor has Washington’s shipbuilding outreach been limited to South Korea. Then-Navy Secretary John Phelan visited Japan in April 2025, meeting Saito and other Japanese defense officials and touring........

© The Diplomat