Trump’s latest move could throw environmental rulemaking into chaos. On Monday, the president signed “a big one”: an executive order mandating that for every new regulation created, two regulations must be eliminated.

The order also says that the total cost of regulatory changes should be zero. Rules related to the military, national security, and foreign affairs are exempted, of course.

Experts are scratching their heads over what this will mean. “The whole rule-writing area is now in complete chaos and environmental rules are going to be caught up in that,” said Georgetown environmental law professor Hope Babcock.