WASHINGTON, Aug 14 (Reuters) - Shares of South Korea's Hanwha Group and Italy's Fincantieri rose on Friday after President Donald Trump's directive opening U.S. Navy shipbuilding to overseas yards.

The companies have the largest U.S. shipyard footprints. Hanwha Ocean Co stock climbed 5.6% while Fincantieri SpA ( FNCNF ) gained 3.2%.

Trump signed a national security memorandum on Thursday that said foreign shipbuilders that make substantial investments in U.S. shipyards and train an American workforce for the jobs they create will be temporarily permitted to build up to two ships in their parent shipyards for quick delivery. 

The memo allows foreign builders to construct three vessel types abroad: surface combatants, consolidated cargo replenishment tankers, and roll-on/roll-off vessels. 

Hanwha is the clear frontrunner, said Bryan Clark, a senior fellow at the Hudson Institute think tank, highlighting South Korea's broad financial commitments to U.S. shipbuilding as the deciding factor. 

Hanwha, which acquired Philly Shipyard in 2024, has since escalated its bet on the U.S. market with a $5 billion pledge to expand the Pennsylvania yard. That investment is part of Seoul's broader commitments under a trade deal with Washington. A Hanwha Defense USA spokesperson said the company was reviewing details of Trump's memo.

Clark said that underlying South Korean government investment puts Hanwha ahead. "You got to make an investment in that shipyard to enable it to produce the things that they're asking for," he said. 

Fincantieri, Europe's largest shipbuilder, has spent more than $800 million on its U.S. shipyards over the past decade, including Fincantieri Marinette Marine in Wisconsin and Fincantieri Bay Shipbuilding. It recently won a $30 million Navy contract for early work on Medium Landing Ship vessels, part of a program that could ultimately cover 35 vessels. Fincantieri did not immediately comment.

Clark expects the policy shift to initially produce tankers and roll-on/roll-off vessels rather than warships, given the cost and complexity of redesigning such ships for the U.S. supply chain.

The U.S. shift complicates Hanwha's non-binding bid for Austal's ( AUTLF ) U.S. operations, since a sale could cost Austal's ( AUTLF ) Australian parent a chance to build two ships domestically under the new rules. Austal ( AUTLF ) rose 5.6% on Friday. Austal ( AUTLF ) did not immediately respond to a request for comment.

Clark said Australia is unlikely to make the necessary investment to qualify, given its commitments under the AUKUS submarine pact.

The Shipbuilders Council of America, which represents U.S. companies, warned that directing shipbuilding overseas undercuts U.S. industry.