US Trade Representative Jamieson Greer has been repeatedly lobbied by a group of US companies who argue applying the framework globally rather than regionally could create market distortions, including shifts from efficient US shortsea maritime transport to land-based modes that are not subject to carbon taxation.

Much of the language used in those submissions is now reflected in the US State Department policy.

A June 26 dated letter submitted to Greer by Congressman Vern Buchanan, vice-chairman of the House Ways and Means Committee and member of the Trade Subcommittee, called on the US Trade Representative to ensure all future trade negotiations take into account each country’s vote on the IMO carbon pricing framework. It also urged the USTR to apply restricted market access or reciprocal tariffs to any country supporting it.

The leaked internal documents cited by the Washington Post suggest that retaliatory measures under consideration include tariffs consistent with Buchanan’s recommendations.

The US State Department would not confirm the authenticity of the leaked documents, but in a statement to Lloyd’s List, a State Department spokesperson said: “We are actively exploring and preparing to act on remedies including tariffs, visa restrictions, or port levies should this effort succeed in the October IMO extraordinary session vote. We will fight hard to protect the American people and their economic interests.”

The threat of US reprisals against IMO member states who do not support the US bid to derail the net zero framework are not wholly new. In April a US statement issued to all London embassies of IMO member states threatened unspecified “reciprocal measures”.

Since then, the US has been engaged in a quiet campaign behind the scenes trying to force IMO member states to reverse their support ahead of the pivotal October vote. However, no details have yet emerged from those meetings to confirm the nature of the trade measures being threatened.

Member states of the IMO agreed on the net zero framework in April following a vote that required a simple majority, 63 member states including China, Brazil and EU countries voted in favour, while just 16 states voted against.

In October, a vote would require a two-thirds majority of 108 member states that ratified the key legislation aiming to reduce shipping pollution. IMO only resorts to voting if there is no agreement on a regulation among member states.

While the US campaign to scupper any vote is unlikely to be able to dissuade a high volume of countries to change their vote, a targeted effort directed at key maritime states remains an outside possibility if the threat of political leverage is effective.

Any amendment to the International Convention for the Prevention of Pollution from Ships, cannot be ratified if countries representing 50% of the world’s tonnage object. The number of countries needed to reach that threshold is relatively small given the high concentration of vessels flagged to the top five flag states: Liberia, Panama, Marshall Islands, Hong Kong and Singapore.