It’s official. When it comes to climate change, there’s now literally everyone else—and then there’s the United States.

Syria, the last remaining holdout from the Paris Agreement on climate change, announced at a United Nations meeting in Germany Tuesday that it will sign the agreement. The Syrian Arab News Agency, a state-sponsored news outlet, also reported that the country’s legislature voted to accept the agreement last month.

Its declaration means that the United States is the only country in the world that has rejected the treaty and promised to withdraw from it.

If the news isn’t exactly pleasant for the Trump administration, which announced the intent to pull the United States out of the Paris Agreement in June, it’s also something of a poor advertisement for the treaty itself. That Syria—war-torn, war crime–committing Syria—has acceded to the Paris accord does not make an obvious case for the United States doing the same.

At the same time, Syria is committing to Paris now because 195 other countries have already signed on. In Britain, France, Germany, Japan, and South Korea, the Paris Agreement is considered a relatively uncontroversial international achievement.

“With Syria on board, now the entire world is resolutely committed to advancing climate action—all save one country,” said Paula Caballero, a climate-policy specialist at the World Resources Institute. “This should make the Trump administration pause and reflect on their ill-advised announcement about withdrawing from the Paris Agreement.”

“Syria’s participation puts an exclamation point on the fact that the U.S. actions are contrary to the political actions, and the sincerely held beliefs, of every other country on the face of the Earth,” said Michael Oppenheimer, a professor of geosciences at Princeton University and a longtime observer of UN climate negotiations.

The United States is “the only powerful country” that has disavowed the treaty, he said. “And that was the case from the day it withdrew.”

“I find it ironic that the government of Syria would say that it wants to be involved [in the Paris Agreement] and that it cares so much in climate and things like CO2 gases,” said Heather Nauert, a spokesperson for the State Department, at a briefing on Tuesday. “If the government of Syria cared so much about what was put in the air, then it wouldn’t be gassing its own people.”

The People’s Council of Syria may not have made the decision to enter the Paris Agreement in the first place. Syria has been engaged in a horrific civil war since 2011, and the areas under government control are tightly ruled by President Bashar al-Assad. The United Nations has implicated Assad in war crimes, including sarin-gas attacks on Syrian children. Assad’s family has run the country since 1971.

Syria has not yet submitted a plan to reduce its greenhouse-gas emissions, as the Paris Agreement requires. In fact, preparing a plan to emit less carbon pollution is just about the only thing the Paris treaty requires.

“I don’t know what the reasons are that Syria chose to focus on this now. It’s got enough problems and doesn’t want to be seen as an outlier in any other way,” Oppenheimer told me.

Its acceptance of the accord can also be seen as a kind of geopolitical troll. Since Nicaragua signed onto Paris last month, Syria was the only remaining country left out of the Paris process. Nicaragua gets almost all of its energy from renewable sources, and it declined to join the treaty in 2015 because it said the accord did not go far enough.

Some analysts have argued that Syria’s decision to join the Paris treaty shows that the agreement is a weak or toothless document. The Paris Agreement, after all, sets few limits on its signatories. Most importantly, it allows countries to set their own emission-reduction goals, rather than imposing them as part of the treaty text.

The United States has never taken issue with the treaty’s toothlessness. In fact, the Paris accord adopts a “bottom-up” strategy in part because the United States has long insisted on it. In 2007, President George W. Bush’s administration began arguing for a “pledge-and-review” climate treaty, similar to the one adopted in Paris. Half a decade later, the Obama White House and the United Nations used a broader version of that plan as they began work on what became the Paris Agreement.

Trump’s critiques of the agreement have focused on its alleged strength. In June, the president said that his “solemn duty to protect America and its citizens” required him to withdraw from the agreement. He and other officials have insisted, to the contrary, that the document is impossibly strong and that it benefits China and India at the expense of the United States.

“We intend to withdraw from the Paris Agreement as soon as we’re eligible to do so, unless the president—and he’s been very clear about saying this—unless he’s able to identify terms of engagement that he feels are more favorable to American businesses, workers, and taxpayers,” Nauert said.

Under the original terms of the Paris Agreement, the United States can announce a new greenhouse-gas reduction plan at any time, and it can elect to remain in the treaty at any time up to 2020. Trump has so far not used this power. Roughly seven out of 10 Americans want America to remain in the Paris accords, according to a Yale University poll conducted earlier this year.

Syria’s accession to the treaty is the first major news to emerge from this year’s UN climate talks, which are being held in Bonn, Germany, this month. The United States cannot formally withdraw from the Paris Agreement until 2020, so a team from the State Department is attending the talks. But experts say its negotiating power will be undercut by America’s looming withdrawal from the process.

“The United States stepped aside from fighting at the beginning of two world wars,” Oppenheimer said. “Then it found it had to join the fight, and it led the fight, and it saved the world from terrible calamities. The United States is going to have to join this fight, too, eventually, and it will have to lead the world in the direction of solving a terrible calamity.”

“The Paris Accord isn’t strong, but it’s a way forward. The world is better with it than without it,” he continued. “I think we’re going to cut emissions, and we’re going to get away from fossil fuels. It’s just a matter of how much damage we bake in in the meantime.”