The US announced in April it would begin applying fees to all arriving Chinese-built and -operated ships after a “Section 301” investigation found Beijing’s dominance in the industry was unreasonable.

Beijing responded last week by announcing “special port fees” on American ships arriving at Chinese ports. Fees on both sides kicked in Tuesday.

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

The US investigation and subsequent measures “severely damage the legitimate rights and interests of Chinese enterprises”, Beijing’s commerce ministry said in a statement.

The Hanwha subsidiaries “assisted and supported the relevant investigation activities of the US government, endangering China’s sovereignty, security and development interests”, it said.

Organisations and individuals in China are banned from cooperating with them starting Tuesday.