President Donald Trump has signed an executive order rolling back Obama-era rules aimed at curbing climate change.
The president said this would put an end to the “war on coal” and “job-killing regulations”.
The Energy Independence Executive Order suspends more than half a dozen measures enacted by his predecessor, and boosts fossil fuels.
Business groups have praised the Trump administration’s move but environmental campaigners have condemned it.
Outside the White House, a few hundred protesters gathered to vent their displeasure at the executive order.
Inside, the president was flanked by coal miners as he signed the order, saying: “My administration is putting an end to the war on coal.
“With today’s executive action I am taking historic steps to lift the restrictions on American energy, to reverse government intrusion and to cancel job-killing regulations.”
During the campaign, he vowed to pull the US out of the Paris climate deal agreed in December 2015.
The regulation has been unpopular in Republican-run states, where it has been subject to legal challenges – especially from businesses that rely on burning oil, coal and gas.
Last year the Supreme Court temporarily halted the plan, while the challenges are heard.
The Trump administration says that scrapping the plan will put people to work and reduce America’s reliance on imported fuel.
It says the president will be “moving forward on energy production in the US”.
“The previous administration devalued workers with their policies. We can protect the environment while providing people with work.”
During the president’s maiden visit to the Environmental Protection Agency, he signed the Energy Independence Executive Order, which cuts EPA regulations in order to support Mr Trump’s plan of cutting the agency’s budget by a third.