BONN - UN climate talks conclude in Bonn Thursday with delegates putting on a brave face despite the threat of an American exodus hanging over their prized global pact to stem global warming.

Envoys from nearly 200 country signatories to the Paris Agreement kept a close eye on Washington throughout their 10-day huddle for any signal about President Donald Trump’s intentions.

On the campaign trail, Trump had threatened to “cancel” the hard-fought pact in which his predecessor, Barack Obama, played an instrumental role in dragging over the finish line in 2015. On the second day of the May 8-18 Bonn talks, the White House announced the postponement of a meeting to discuss America’s future in the deal, compounding the uncertainty. A historically small US delegation at the annual round of technical negotiations was thus also left in the dark.

“I personally have met with the head of the (US) delegation a couple of times and... he’s just very open in repeating: ‘Our position is under review’,” UN climate chief Patricia Espinosa said on Thursday.

But negotiators insisted that work progressed on outlining a nuts-and-bolts “rule book” for implementing the agreement’s goals, despite the ever-present “Sword of Damocles”, as one put it.

Many commented that the mood was a positive one, and said the American delegation participated in the talks, though cautiously.

There is the fear that whatever progress is made now can easily be swept off the table when the negotiators get together next, perhaps encountering a new US team with a different brief.

“The rest of the world must continue to work towards progress together,” said Nazhat Shameem Khan of Fiji, who will preside over the next ministerial-level round of climate talks in November. “We shouldn’t give up because one of the community, one of the family, has decided that they will not walk with us.”

Observers pointed to the importance of upcoming meetings of the G7 and G20, strategic country groupings of which the US is a member, in putting pressure on Trump, who has described climate change as a “hoax” perpetrated by China.

“We work very hard together with many other friends in the world to convince the US that staying in the Paris Agreement is the right way to go,” Jochen Flasbarth, Germany’s state secretary for the environment, told journalists in Bonn.

“Germany stays committed to the international UN climate process. We believe that it is irreversible and many, many countries indicate to us that nobody has the intention of thinking about another format, another track apart from the UN.”

There are fears in some quarters that an American withdrawal may encourage others to follow suit, or at least harm the collective will, built up over two decades of tough negotiations, to act on climate change.

The Paris Agreement commits signatories to limiting average global warming to two degrees Celsius (3.6 degrees Fahrenheit) over pre-Industrial Revolution levels.

This will be achieved by limiting emissions from burning coal, oil and gas. But the fossil fuel lobby in America exerts a strong influence over climate politics, both national and international.

Fijian Prime Minister Frank Bainimarama, whose island nation is at high risk of climate change-induced sea level rise, stressed that rich coastal cities face the same threat, and named Miami, New York, Venice, and Rotterdam.

“No-one, no matter who they are or where they live, will ultimately escape the impact of climate change,” the premier told negotiators in Bonn, where he made a special appearance.

“We are all vulnerable and we all need to act.”

His warning was underscored by a new study in Nature Scientific Reports which found that level rise of “only 10 cm (four inches)” doubles flooding potential for cities on the North American west coast - citing Vancouver, Seattle, San Francisco and Los Angeles - as well as the European Atlantic coast.

“We don’t know,” what Trump will eventually decide, “but we won’t stop our work even if the result is a negative one,” Khan said.

“We hope very much that they will remain in the Paris Agreement and that they will walk with the rest of the family towards this very urgent goal that the planet is facing.”