Joo Won-ho, right, head of HD Hyundai Heavy Industries' naval and special ship business unit, and Philly Shipyard CEO Steinar Nerbovik sign a memorandum of understanding at the latter's office in Philadelphia, Pennsylvania, April 12. Courtesy of HD Hyundai

HD Hyundai Heavy Industries (HHI) and Philly Shipyard agreed to cooperate in the U.S. naval ship market, the HD Hyundai subsidiary said Wednesday, months after the Korean shipbuilder's chief rival, Hanwha Ocean, indicated its intention to acquire the Philadelphian shipyard.

The agreement was signed at Philly Shipyard in Pennsylvania, April 12 (local time), while HD HHI officials were in the U.S. to attend the Sea Air Space 2024 maritime defense expo in Maryland.

HD Hyundai has already been supplying designs and materials for commercial vessels to Philly since 2005.

Under their latest agreement, the Korean firm seeks to supply designs and materials for naval and public vessels built and maintained by the Philadelphian shipyard for the U.S. government.

"We will expand our presence in the global defense industry through our cooperation with the U.S. firm in construction, maintenance, repair and overhaul of naval and public vessels," said Joo Won-ho, head of HD HHI's naval and special ship business unit.

HD Hyundai said its officials had a chance to look around Philly's shipbuilding sites, so that both companies could share their technologies for the construction and maintenance of warships.

"Philly Shipyard and HD HHI have a long and gratifying history of working together, and we are honored by the idea of future cooperation on opportunities for U.S. government and commercial shipbuilding projects," Philly Shipyard CEO Steinar Nerbovik said.

As a subsidiary of Norwegian energy firm Aker, Philly Shipyard was founded in 1997 on part of the site of the Philadelphia Naval Shipyard.

Because the U.S. Jones Act prohibits any foreign-built, foreign-owned or foreign-flagged vessels from engaging in coastwise trade within the U.S., Hanwha Ocean has been considering buying Philly Shipyard, amid its intensifying competition with HD HHI in the global naval ship market.

Last year, the Hanwha subsidiary reportedly sent its officials to the Philadelphia shipyard. Hanwha Ocean's establishment of its U.S. holding company late last year was also seen as a preparatory step to take over the shipyard.

In February, the Korean company confirmed it had considered acquiring Philly Shipyard.

Securities analysts have also kept a close watch on Hanwha Ocean's efforts to acquire Philly Shipyard and Australia's Austal, which has supplied naval ships to the navies of the U.S. and Australia.

"Hanwha Ocean's special ship business will gain momentum, thanks to its anticipated expansion in the global warship construction and maintenance markets through its acquisition of a U.S. shipyard," SK Securities analyst Han Seung-han said in a report published earlier this month.