With the U.S. set to enact new fees against maritime vessels with Chinese owners and operators, China is hitting back with new regulations of its own.

In a September 29 release, China's State Council announced new countermeasures against any countries that impose "discriminatory bans" or restrictions that target Chinese maritime operators, vessels or crew. The countermeasures took effect on September 28, and will remain in place "unless relevant treaties or agreements offer adequate and effective remedies." No other details were released as to what exactly the measures entail.

Starting in the U.S. on October 14, Chinese-operated or owned vessels calling U.S. ports will be subject to a $50-per-net-ton fee, while Chinese-built ships will pay $18 per net ton (or $120 per container discharged, whichever is higher). The fee is also capped at five assessments per vessel annually, and will be charged per rotation at U.S. ports, rather than at each call in a single string. However, with just two weeks to go before the fees come into force, several key questions remain as to how they'll be collected and enforced. 

Read More: WSC: Need for Clarity on U.S. Port Fees for Chinese Ships

"Ship operators and owners are scrambling to understand the (policy) and its implications, which in many respects remain unclear," said law firm Vedder Price in a September 9 blog post.

As Vedder Price points out, the language of the U.S. Trade Representative's fee structure is vague in several respects, including its definition of a Chinese-owned vessel, what qualifies as a "rotation" for a vessel calling U.S. ports, and whether the annual cap is for a calendar year or a rolling 12 months starting with the first time a fee is assessed. Given those questions, "not everyone is convinced that the October 14th USTR port call fees will materialize," said Freightos in a September 16th client note, particularly as the Trump administration continues to negotiate with China on tariffs and other potential trade restrictions.