The United States has threatened to impose visa restrictions and sanctions on countries that vote in favor of a plan proposed by a UN agency to reduce greenhouse gas emissions from ocean shipping.

This week, UN member states are scheduled to vote on a proposed zero net emissions framework by the International Maritime Organization (IMO) to curb global carbon dioxide emissions from the international shipping sector, which handles about 80% of global trade and accounts for nearly 3% of global greenhouse gas emissions.

Operators of large tankers, under pressure from investors to combat climate change, generally agree that a global regulatory framework is critical to accelerate decarbonization. However, some of the world’s largest oil tanker companies have expressed “major concerns” about the proposal.

US Secretary of State Marco Rubio, Energy Secretary Chris Wright, and Transportation Secretary Sean Duffy said in a joint statement, “The US administration unequivocally rejects the proposal presented to the IMO and will not tolerate any action that increases costs on our citizens, energy suppliers, shipping companies, their customers, or tourists.”

Supporters of the IMO proposal argue that without global regulation, the shipping sector will face a patchwork of regulations and rising costs without effectively curbing greenhouse gas emissions.

US officials said Friday that the United States is considering countermeasures against IMO member states that support the plan.

This could include barring ships flying the flags of those countries from entering US ports, imposing visa restrictions and fees, and sanctioning officials “who sponsor climate policies led by activists.”