The United States has warned members of the United Nations’ International Maritime Organization (IMO) against supporting a proposed global carbon tax on commercial shipping emissions. The US has indicated that it would consider retaliatory actions if such a levy is introduced.

The emissions tax proposal seeks to charge vessels based on their carbon output, aiming to reduce the environmental impact of global shipping. The US, however, strongly opposes the measure and has announced it will not participate in this week’s IMO discussions on the topic.

American representatives emphasized that if the tax is enacted, reciprocal measures may be taken to counterbalance any financial burden placed on US-operated ships. The position reflects broader concerns over potential economic disadvantages and disruptions to trade routes involving American maritime interests.

During the same week, the IMO’s Marine Environment Protection Committee is holding meetings to define international standards for marine fuel. These are intended to encourage cleaner energy use across global shipping fleets, forming a critical step in the push for decarbonization.

IMO Secretary-General Arsenio Dominguez reiterated that the planned regulations will be mandatory for all ships operating internationally, as part of the organization's efforts toward achieving a net-zero future for the maritime sector.

The US warning adds a new dimension to the ongoing debate about global climate regulation and highlights tensions between environmental objectives and national economic strategies.