Today, Syria announced that it would sign the Paris climate agreement — a landmark deal that commits almost 200 countries to reducing greenhouse gas emissions to fight global warming. With Nicaragua also joining the deal last month, the United States is now the only country in the world that opposes it.

In June, President Donald Trump announced that the US will withdraw from the Paris climate accord, unless it is renegotiated to be “fair” to the United States. But other countries in the deal, such as France, Germany, and Italy, said that’s not possible. The Trump administration is also taking steps to roll back regulations passed under former President Barack Obama to achieve the emissions reduction goals set under the Paris deal. The US is the second largest emitter of heat-trapping greenhouse gases in the world after China.

one of the most comprehensive climate change agreements ever passed

Reached at the end of 2015, the Paris accord is one of the most comprehensive climate change agreements ever passed. It is notable because it included countries like China, which pollute heavily but have not signed on to climate deals before. Nicaragua and Syria both didn’t sign the deal at the time: Nicaragua claimed it wasn’t ambitious enough, but reversed its course last month and decided to sign the deal anyway, calling it “the only instrument that currently allows this unity of intentions and efforts,” according to The New York Times.

Syria didn’t join the deal initially because it’s been embroiled in a civil war since 2011. The Syrian government is under European and American sanctions, so it couldn’t send representatives abroad to negotiate or sign the agreement, according to The New York Times. Today, however, during United Nations climate talks, the country announced it would sign the Paris deal. It’s not clear what has changed, the Times says, and Syria still has to submit its targets for cutting greenhouse gases.

Still, today’s announcement leaves the United States more isolated than ever. “With Syria’s decision, the relentless commitment of the global community to deliver on Paris is more evident than ever,” Paula Caballero, director of the climate change program at the World Resources Institute, told the Times. “The US’s stark isolation should give Trump reason to reconsider his ill-advised announcement and join the rest of the world in tackling climate change.”