The head of the Environmental Protection Agency in effect declared trench warfare on environmental groups on Monday, ending a practice he dubbed “Sue & Settle” by which the EPA would often settle lawsuits brought by outside groups in an attempt to get the agency to enforce its own rules.

“As of today with this directive and the memorandum, we’re no longer going to be involved in that practice,” Pruitt told a small group of reporters, including TPM, Monday morning at the EPA. “It’s a regulation through litigation process.”

Pruitt painted the policy as a way that environmental groups profited off the agency during the Obama years, while those groups worked together to circumvent the normal rule-making process and create more stringent environmental regulations.

“We should engage in rule-making that takes into consideration the voices that will be impacted across the country,” he said. “What this sue-and-settle practice has done historically has bypassed that altogether.”

The rule change could force environmental groups to spend much more time and effort on lawsuits aimed at making the EPA enforce its own rules and abide by agreed-upon timelines—spreading them thinner and making it harder for them to expend effort on other, more complicated cases. The EPA’s decision to refuse to reimburse lawyers’ fees also could be costly to environmental groups, as well as make it harder and less likely for average citizens and localities to undertake lawsuits to get the EPA to do what it’s legally required to do.

Pruitt pledged that the agency would no longer reimburse attorneys’ fees in cases where it decides to avoid a lawsuit, arguing that both environmental and business groups had abused it to enrich themselves in the past.

“This is not particular to one type of plaintiff,” he said. “There should be no attorneys’ fees paid, period, no matter who the plaintiff is.”

Combined with measures to slash staff, a pattern of issuing fewer and lighter fines, and the rollback of Obama-era rules that crack down on greenhouse gas emissions from power plants to mitigate the effects of climate change, Pruitt’s latest move is part of an overall shift at Trump’s EPA that’s radically more friendly to big business and hostile towards environmental groups.

The U.S. Chamber of Commerce, for instance, has railed against “Sue & Settle” for years.

The new memorandum formalizes a position of fighting every lawsuit tooth-and-nail that Pruitt had announced early in his tenure at the EPA. Back in February, he’d promised he wouldn’t allow “regulation through litigation.” The Justice Department also has stopped negotiating settlements that end up with payments to outside groups to cover attorneys’ or other fees.

Environmental groups fired back at Pruitt after his new declaration.

“Scott Pruitt and his polluter cronies continue to perpetrate lies about the law as an excuse for refusing enforcing it — but when it comes to the law, the truth has a way of catching up with you,” Sierra Club Environmental Law Program Director Pat Gallagher said in a statement. “If Pruitt thinks that by frivolously litigating deadline cases he will deter the Sierra Club or other citizen groups from holding him accountable in court, he should think again – we will not be deterred.”

Fewer than a dozen reporters were included at the event with Pruitt, and some of them, including TPM, rarely if ever cover the environmental beat closely—a fact that frustrated some environmental reporters who weren’t invited to attend:

Would be fascinated to know how he defines 'sue and settle' vs. regular settlements. But alas, @EPA didn't invite us https://t.co/mLPW0dOttu — Timothy Cama (@Timothy_Cama) October 16, 2017

.@EPAScottPruitt is meeting with reporters at an invite-only event. My sources tell me it's about a "sue and settle" initiative. https://t.co/Bht276MsTp — Zack Colman (@zcolman) October 16, 2017

Hear the full audio of the event below:

This story was updated at 1:15 p.m. to include the Sierra Club’s response.