President Donald Trump signed an executive order Monday directing the United States to again withdraw from the landmark Paris climate agreement, dealing a blow to worldwide efforts to combat global warming and once again distancing the U.

President Donald Trump says he will again withdraw the United States from the landmark Paris climate agreement

Quitting the Paris Agreement triggers a cascade of real-world impacts and signals the beginning of an aggressive agenda to undo U.S. climate policy.

The United States would be one of only four countries outside the Paris Agreement, which is designed to reduce global greenhouse gas emissions.

President Donald Trump is once again withdrawing the United States from the Paris climate accords, pulling the nation whose factories, cars and power plants contributed the most cumulative planet-heating pollution to the atmosphere out of the first global pact to slash carbon emissions enough to prevent the world’s average temperature from reaching dangerous new heights.