STORY: The U.S. and China are charging additional tit-for-tat port fees on ocean shipping firms in the latest escalation of their trade war.These charges will affect vessels transporting everything from toys to crude oil.China has already begun collecting the fees from ships that are U.S.-owned, operated, built or flagged.However, Chinese-built vessels are exempt.According to state media, exemptions also apply to empty ships entering Chinese shipyards for repairs.Meanwhile, the U.S. will begin collecting its fees on Tuesday. Earlier this year, the Trump administration set out a plan to target China-linked ships in a bid to weaken Beijing’s dominance of global shipping and boost American shipbuilding.A prior investigation under former President Joe Biden found that China uses unfair practices to control the maritime, logistics, and shipbuilding sectors, clearing the way for the new penalties.One analyst said Chinese state-owned shipping giant COSCO could be hit hardest, potentially absorbing nearly half of the estimated $3.2 billion in fees by 2026.Despite the turmoil, shares in COSCO rose around 3% in early trading on Tuesday.The company announced a plan to buy back shares worth around $210 million to protect its value and reassure investors.COSCO did not immediately respond to a Reuters query about the potential impact of the port fees.