US authorities have warned they will take retaliatory measures against any country supporting an international carbon tax on maritime transport. This announcement comes just days ahead of a crucial vote within the International Maritime Organization (IMO), where members are set to decide on a proposal to implement a global carbon levy on ship emissions.
Secretary of State Marco Rubio, along with the Secretaries of Energy and Transportation, described the proposed measure as “neo-colonial” in a statement. Washington asserts that the implementation of such a fiscal mechanism on carbon dioxide (CO₂) emissions — referred to by the acronym NZF — would harm US economic interests and negatively impact supply chains and consumers.
Anticipated economic repercussions
US officials estimate the tax could raise shipping costs by 10% or more. Authorities claim that such a levy on carbon emissions would directly affect shipping companies, energy suppliers and importers, leading to price increases for citizens and businesses.
The NZF tax proposal would be the first global fiscal mechanism adopted by a United Nations agency, according to the statement. The London-based IMO oversees international shipping regulations and aims to reduce the sector’s total emissions in line with its environmental goals.
A stance aligned with current US policy
Since returning to power, President Donald Trump has reoriented US energy policy in favour of fossil fuels, rolling back multiple international climate commitments. The White House withdrew from the Paris Agreement and enacted a series of deregulation measures aimed at supporting the oil, gas and coal industries.
This shift has resulted in growing hostility toward multilateral initiatives perceived as burdensome to the US economy. At the United Nations, President Trump previously described climate change as “the greatest scam” in history, rejecting scientific consensus and advocating for complete economic sovereignty.
Targeted economic sanctions under consideration
Among the measures under consideration are visa restrictions and increased port fees for vessels owned by or registered in countries supporting the carbon tax. These steps are intended to discourage any endorsement of a system the US considers imposed without its consent.
“We will fight fiercely to protect our economic interests,” the statement’s signatories declared, reaffirming the United States’ strong opposition to any international carbon tax applied across the global commercial fleet.
