Trump explained this in accordance with the Paris climate agreement

The world met in Paris in December 2015 to fight climate change, tonight, despite calls from other world leaders, President Trump is ready to pull the United States out of the deals, uniting only Syria and Nicaragua.

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The agreement – signed two years ago – was the basis for an international commitment to climate change. It was seen as the first comprehensive attempt to keep the global average temperature rise below 2 degrees Celsius.

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