The United States has joined Nicaragua and Syria as the only nations on earth that have rejected the landmark Paris climate accord which had been signed by 197 countries and ratified by 146, including the US.
President Donald Trump called the treaty, which was signed by his predecessor, Barack Obama, as unfair to the US and described his decision as "a reassertion of our sovereignty."
But key countries like Germany, France and Italy ruled out any renegotiation and pledged to redouble their efforts to address the challenge of climate change with or without the United States. China and India also reaffirmed their commitment to the agreement.
Many high-profile American executives, including Disney's Robert Iger, Facebook's Mark Zuckerberg and Tesla's Elon Musk, had tried to convince Trump not to pull out. Musk and Iger have resigned from Trump's advisory council.
While the agreement have entered into force in 2016, the withdrawal of a top emitter of fossil fuel emissions makes it doubtful whether the goal of slowing climate change and mitigating the impact on human lives and the environment. Trump accused China, India and other countries of using the agreement as a means of gaining an unfair advantage over the US, as it provides funds and requires less stringent reductions on developing economies.