The United States is now the only country on the planet not part of the Paris Climate Agreement.

On Tuesday, Syria announced that it would sign the historic accord to limit global warming. The surprising declaration came at COP23, the UN Climate Change Conference that is currently taking place in Bonn, Germany. The move comes on the heels of Nicaragua signing the pact in October.

Years in the making, the Paris Agreement set the target of holding global warming to 2°C (3.6°F) above pre-industrial levels. To achieve this goal, nearly 200 countries submitted individual voluntary emissions reduction plans known as nationally determined contributions (NDCs).

When the deal was struck in 2015, Syria was in the midst of a destructive civil war and Nicaragua refused to sign because if felt the agreement did not go far enough to rein in carbon pollution. The US on the other hand, under the Obama Administration, played a critical role in making the deal a reality. But President Trump, who has called climate change a “hoax”, announced plans to withdraw the US from the global pact earlier this year.

Following the rules of the agreement, however, the US cannot officially pull out of the deal until 2020. In the meantime, the administration says it will only re-enter the global accord if it can renegotiate more favorable terms. The rest of the world, however, seems ready to move forward on this critical issue without the US.

The US is the only country not part of the Paris Climate Agreement. Credit: Quartz