China’s Ministry of Transport announced Tuesday a set of 10 implementation measures as the country begins imposing special port fees on ships owned or operated by U.S. enterprises, organizations, and individuals. The move aims to safeguard the legitimate rights and interests of Chinese shipping companies while ensuring fair competition in international shipping, according to the ministry’s website.

The fees also apply to vessels owned or operated by entities in which U.S. enterprises, organizations, or individuals hold a direct or indirect stake of 25% or more, as well as all U.S.-flagged and U.S.-built ships.

Exemptions include vessels built in China under the first to fourth categories, ships entering Chinese shipyards solely for repairs, and any other vessels determined by the authorities to be exempt.

The ministry outlined a phased escalation for the fees on eligible U.S. vessels berthing at Chinese ports. The initial fee is set at 400 yuan ($56) per net ton starting Tuesday, with annual increases scheduled every April 17 over the next three years.