Donald Trump is set to announce his decision on the continued US participation in the Paris climate change agreement later on Thursday.
According to various reports, the US president will pull the country out of the agreement, which was signed in 2015 with the aim of reducing carbon and greenhouse gas emissions.
The accord was chaired by the United Nations Framework Convention on Climate Change (UNFCCC) and became effective from last November.
Trump had made the pledge to withdraw from the agreement during the presidential election campaign, but in recent weeks administration officials have said his views on the accord were "evolving" because he was hearing both sides.
Meanwhile, reports of a potential withdrawal prompted allies like Angela Merkel and other world leaders to pressure Trump for a more strident commitment to the agreement.
The US President revealed on Twitter when he would make the announcement of his decision:
If the US pulls out, it will join Nicaragua and Syria in being the only countries not taking part.
At the current time, the US has the second largest amount of carbon emissions in the world.