BONN, Germany >> The senior American diplomat at the United Nations climate talks here told world leaders today that the United States would remain engaged in global climate change negotiations even as it planned to exit the Paris agreement “at the earliest opportunity.”

Judith G. Garber, a State Department acting undersecretary, gave the first official American remarks to the U.N. climate body since President Donald Trump announced in June that he would abandon the Paris deal. It was a far more conciliatory message than a presentation earlier in the week by White House officials promoting fossil fuels, which drew catcalls and a walkout.

“President Trump has made clear the U.S. position with respect to the Paris agreement,” Garber said. “Although he has indicated that the United States intends to withdraw at the earliest opportunity, we remain open to the possibility of rejoining at a later date under terms more favorable to the American people.”

Garber’s address made no mention of coal while promising to help other countries “adapt to the impacts of climate change.” It was the only mention of climate change in the three-minute presentation, but that was one more than many Trump administration critics had expected. And in contrast to the noisy protests that greeted the White House fossil fuel event, Garber’s speech in a tightly-controlled plenary hall was met with polite applause.

The Trump administration has sent two sets of officials to the Bonn climate talks, where 195 nations are gathered to seek ways to strengthen the Paris agreement. White House officials, led by George David Banks, Trump’s international energy adviser, have been far more visible, talking to reporters and mingling with environmental activists as well as energy executives.

But because the Trump administration cannot officially exit the Paris climate agreement until 2020, it also sent a small State Department team to negotiate details of international climate policy, like greater transparency for emissions reporting from China and India.

Environmentalists here said they found Garber’s message confusing, and a sign of the awkward tightrope that U.S. diplomats are walking as they work on a deal Trump has disavowed.

“The few people in Bonn who were interested in this speech heard a muddled explanation of Trump’s dangerously incoherent climate policy,” said John Coequyt, global climate policy director at the Sierra Club.

Todd D. Stern, the former State Department climate envoy under President Barack Obama who helped design the Paris agreement, traveled to Bonn to tell his former counterparts that he believed the United States’ absence from the global accord would be short-lived.

He said his message to other nations was “not to let the retrograde, head-in-the-sand conduct in Washington divert you from your purpose and your course and your commitment. It’s too important to let that happen. And I just firmly believe the U.S. will be back in.”

White House officials have declined to say what new and more favorable terms Trump seeks. Banks said that was a conversation Trump would have to have with other world leaders. He did not indicate when that might occur or if it was on the president’s to-do list.

Stern said the White House itself was divided on the question of whether or how to find a way back into the accord.

“I don’t think it’s clear who are the key decision-makers, or who will be the key decision-makers on a road that’s three years long,” he said.

In her remarks, Garber noted that the United States had cut its greenhouse-gas emissions 11.5 percent through 2005, thanks to both public policies and private sector innovations in natural gas and solar power. But she pointedly avoided any promises to cut emissions further, as the Obama administration had done under the Paris agreement.

This week, scientists reported that the pace of emissions reductions in the United States likely slowed in 2017. For the world to meet its climate goals, the country would almost certainly need to accelerate its efforts.

“The United States will continue to support a balanced approach to climate mitigation, economic development and energy security that takes into consideration the realities of the global energy mix,” Garber said.

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