“I will always put the needs of our country first,” Mr. Trump said. “That is why we are withdrawing from one-sided international deals,” he added, citing the Trans-Pacific Partnership and the Paris agreement.

Yet the United States cannot formally leave the accord until 2020, and in the interim administration officials have said they will continue to protect American interests, which essentially translates into helping to write the Paris agreement’s rule book. Secretary of State Rex W. Tillerson and Mr. Trump’s national security adviser, Lt. Gen. H. R. McMaster, have both dangled the possibility that some as-yet undefined improved terms might one day persuade the president to reconsider.

This ambiguous position will be on stage at the meeting of the United Nations Framework Convention on Climate Change, at which representatives of the nearly 200 signers to the Paris agreement will gather beginning on Nov. 6 in Bonn.

“The U.S. is still at the table,” said James L. Connaughton, who served as an environmental adviser to George W. Bush. “It’s very important for the United States to have a presence. The U.S. is looked to and heavily engaged regardless of differences of opinion.”

The two-week session promises to be a volatile mix of anger toward the United States for declaring its intention to withdraw from the accord, mixed with lingering hope it might stay. Developing countries, particularly some of the most vulnerable to climate change, will most likely use the spotlight of the forum to denounce the Trump administration’s growing ranks of climate deniers and recent moves to repeal regulations limiting greenhouse gases.