One of the world’s most vulnerable countries to the fallout from climate change has won a landmark legal battle, giving countries new ammunition to pursue some of the planet’s biggest emitters.

In a landmark decision, the International Court of Justice found that polluting countries are now legally obligated to address global warming. In a unanimous ruling by a panel of 15 judges, the court said high-emitting countries do have legal obligations under international law to address the “urgent and existential threat” of climate change.

The ICJ issued an opinion on climate change that stated the obligations of the Paris Agreement come with legal liability. A concern raised by Trump as early as 2017.