HONG KONG (AP) -- China's Commerce Ministry said Tuesday it was banning dealings by Chinese companies with five subsidiaries of South Korean shipbuilder Hanwha Ocean in the latest swipe by Beijing at U.S. President Donald Trump's effort to rebuild the industry in America.

The ministry also announced that it was also investigating a probe by Washington into China's growing dominance in world shipbuilding. It said the U.S. probe threatens China's national security and its shipping industry and cited Hanwha's involvement in the investigation.

The U.S. Trade Representative launched the Section 301 trade investigation in April 2024. It determined that China's strength in the industry was a burden to U.S. businesses.

International shipping and shipbuilding have become a recent focus of trade friction between Washington and Beijing. Each side has imposed new port fees on each others' vessels that took effect on Tuesday.

The sanctioned entities are Hanwha Shipping LLC, Hanwha Philly Shipyard Inc., Hanwha Ocean USA International LLC, Hanwha Shipping Holdings LLC and HS USA Holdings Corp.

In late 2024, Hanwha acquired the Philly Shipyard in Pennsylvania for $100 million. It announced in August that it plans to invest $5 billion in new docks and quays as part of its support for U.S. efforts to restore globally competitive shipbuilding capacity.

Hanwha Ocean also has an agreement on ship repairs with the U.S. Navy.

China said its new port fees would apply to ships owned by U.S. companies or other entities or individuals, those operated by U.S. entities including those having a U.S. stake of 25% or more, vessels flying a U.S. flag and vessels built in the United States.

U.S. businesses represents just 2.9% of world fleet ownership by capacity and 0.1% of global shipbuilding tonnage. Trump has vowed to help rebuild the industry as part of his broader push to expand U.S.-based manufacturing.

China sanctions 5 US units of South Korean shipbuilder Hanwha Ocean over probe by Washington