The Trump administration announced Monday it would repeal the Clean Power Plan, a 2015 regulation that sharply curbed greenhouse gas emissions from power plants and a key part of President Barack Obama’s environmental legacy.

At an event in Hazard, Kentucky, Environmental Protection Agency Director Scott Pruitt said the prior administration had overreached in enacting the rule, which pushed U.S. power plants to cut fossil fuel emissions by a third from 2005 levels by 2030.

“The war on coal is over,” Pruitt said. “Tomorrow in Washington, D.C., I will be signing a proposed rule to roll back the Clean Power Plan.”

Environmental groups strongly opposed Pruitt’s rollback plan.

“This is a reckless retreat that will hurt our children and grandchildren. The real-world results will be more asthma attacks, more health problems, more air pollution, and a more dangerous future for our families,” said Fred Krupp, president of the Environmental Defense Fund, in a news release.

The announcement is no surprise from Pruitt or the Trump administration. In April, President Trump signed an executive order calling for a review and possible repeal of the plan, which was on hold anyway pending a legal challenge from 26 states.

Pruitt has long kept close ties to the fossil fuel industry. Since 2002, his various campaigns for state senate and attorney general of Oklahoma received over $300,000 from that industry. While he was attorney general of Oklahoma, he sued the EPA 14 times and had fossil fuel groups help draft letters he sent to oppose federal energy regulation.

As part of the federal agency rule-making process, the EPA must now hold public hearings; solicit public comments; and respond to legal, scientific, and economic objections to the rule change.

When it was introduced, the Clean Power Plan met with praise from environmental groups and disapproval from fossil fuel proponents. It set state-by-state targets for carbon emissions reductions from power plants, with an ultimate goal of reducing carbon emissions by 30 percent from their 2005 levels. To achieve these targets, power plants had to invest in new renewable technologies or make their current facilities cleaner and more energy-efficient.

Withdrawing from the Clean Power Plan will make it harder for the U.S. to comply with the landmark Paris climate agreement, which required that the U.S. reduce greenhouse gas emissions to 26 percent to 28 percent below 2005 levels by 2025. The goal of the Paris agreement was to decrease global carbon emissions in a bid to cap global temperature increases to 2 degrees Celsius over pre-industrial levels.

President Trump has said the U.S. will formally withdraw from the 2015 accord — under which 195 countries agreed to reduce carbon emissions — but has also said he might try to “renegotiate” it.