Russia on Monday blocked a United Nations Security Council draft resolution, under negotiation for many months, that for the first time would have defined climate change as a threat to peace.

The resolution, which enjoyed wide-ranging support, would have significantly expanded the criteria used by the most powerful U.N. agency to justify intervening in armed conflicts around the world.

Russia’s derailment of the measure underscored the challenges faced by the United Nations in uniting the global community to combat climate change, which Secretary-General Antonio Guterres and others have called an existential threat.