President Donald Trump on Tuesday signed an order to undo Obama-era climate change regulations, keeping a campaign promise to support the coal industry and calling into question U.S. support for an international deal to fight global warming.

Flanked by coal miners and coal company executives, Trump proclaimed his "Energy Independence" executive order at the headquarters of the Environmental Protection Agency.

The move drew swift backlash from a coalition of 23 states and local governments, as well as environmental groups, which called the decree a threat to public health and vowed to fight it in court.

The order's main target is former President Barack Obama's Clean Power Plan, which required states to slash carbon emissions from power plants - a key factor in the United States' ability to meet its commitments under a climate change accord reached by nearly 200 countries in Paris in 2015.

Trump's decree also reverses a ban on coal leasing on federal lands, undoes rules to curb methane emissions from oil and gas production and reduces the weight of climate change and carbon emissions in policy and infrastructure permitting decisions. Carbon dioxide and methane are two of the main greenhouse gases blamed by scientists for heating the earth.

"I am taking historic steps to lift restrictions on American energy, to reverse government intrusion and to cancel job-killing regulations," Trump said at the EPA.

The room was filled with miners, coal company executives and staff from industry groups, who applauded loudly as Trump spoke. Shares in U.S. coal companies edged higher in response.

The wide-ranging order is the boldest yet in Trump’s broader push to cut environmental regulation to revive the drilling and mining industries, a promise he made repeatedly during the 2016 presidential campaign.

Energy analysts and executives have questioned whether the moves will have a big effect on their industries, and environmentalists have called them reckless.

"I cannot tell you how many jobs the executive order is going to create, but I can tell you that it provides confidence in this administration’s commitment to the coal industry," Kentucky Coal Association president Tyler White told Reuters.

Environmental groups heaped scorn on Trump's order, arguing it was dangerous and went against the broader global trend toward cleaner energy technologies. A coalition of mostly Democrat-led states and local governments issued a statement saying they would oppose the order in court.

"We won’t hesitate to protect those we serve — including by aggressively opposing in court President Trump’s actions that ignore both the law and the critical importance of confronting the very real threat of climate change," the coalition, led by New York Attorney General Eric Schneiderman, said in a statement.

The coalition includes states such as California, Massachusetts and Virginia, as well as cities including Chicago, Philadelphia and Boulder, Colorado.

PARIS DEAL NOT ADDRESSED

U.S. presidents have aimed to reduce U.S. dependence on foreign oil since the Arab oil embargo of the 1970s, which triggered soaring prices. But the United States still imports about 7.9 million barrels of crude oil a day, almost enough to meet total oil demand in Japan and India combined.

An overwhelming majority of scientists believe that human use of oil and coal for energy is a main driver of climate change, causing a damaging rise in sea levels, droughts and more frequent violent storms.

But Trump and several members of his administration have doubts about climate change, and Trump promised during his campaign to pull the United States out of the Paris climate accord, arguing it would hurt U.S. business.

Since being elected, Trump has been mum on the Paris deal and the executive order does not address it.

Christiana Figueres, former executive secretary of the United Nations Framework Convention on Climate Change who helped broker the Paris accord, lamented Trump's order.

"Trying to make fossil fuels remain competitive in the face of a booming clean renewable power sector, with the clean air and plentiful jobs it continues to generate, is going against the flow of economics," she said.

The order directs the EPA to start a formal process to undo the Clean Power Plan, which was introduced by Obama in 2014 but was never implemented in part because of legal challenges brought by Republican-controlled states.

The Clean Power Plan required states to collectively cut carbon emissions from power plants by 32 percent below 2005 levels by 2030.

Some 85 percent of U.S. states are on track to meet the targets despite the fact the rule has not been implemented, according to Bill Becker, director of the National Association of Clean Air Agencies, a group of state and local air pollution control agencies.

Trump’s order also lifts the Interior Department's Bureau of Land Management temporary ban on coal leasing on federal property put in place by Obama in 2016 as part of a review to study the program's impact on climate change and ensure royalty revenues were fair to taxpayers.

It also asks federal agencies to discount the cost of carbon in policy decisions and the weight of climate change considerations in infrastructure permitting, and it reverses rules limiting methane leakage from oil and gas facilities.