It is unclear what a negotiation would look like. For one, the Paris Agreement is the result of more than two decades of climate diplomacy. And while the accord requires signatories to submit plans to reduce their greenhouse gas emissions, it gives them wide latitude to create plans to meet those targets and does not bind them legally to achieve them.

Pruitt said any deal that requires the United States to set emissions targets that are enforced through domestic regulations or laws should be ratified by the Senate.

The United States has largely reduced its carbon emissions through technological innovation, particularly through advanced drilling methods that have allowed American producers to tap vast supplies of natural gas. Pruitt said the United States could contribute to global emissions reductions by exporting its technology and know-how.

There is significant opposition to the key technology behind the U.S. shale gas boom — a process called hydraulic fracturing — in Europe. The State Department under Hillary Clinton attempted to encourage natural gas fracking in other countries, but the program has had limited success.

Watch: Fact-checking Trump’s Paris speech