US President Trump said the time for a US withdrawal from the Paris climate agreement was now.
In a tweet on Monday, Mr Trump said that “the time for #ParisAccords withdrawal is now”.
“If we do nothing, the world will not be able to keep its promise to fight climate change,” he added.
“If #Paris accords withdraws, we will be left in a worse position to make global climate change a reality.
This is a direct result of our leadership in Paris,” he said.”
The time is now to act to stop the downward spiral of #ParisAgreements withdrawal,” he wrote.
Mr Trump has repeatedly criticised the accord, saying it would lead to more extreme weather and global warming.
The agreement was reached in 2015 by 196 countries and more than 160 countries have pledged to reduce carbon emissions.