BISMARCK, N.D. (AP) — North Dakota Gov. Jack Dalrymple is ordering an emergency evacuation of Dakota Access pipeline protesters who are camping on U.S. Army Corps of Engineers land.

The Republican governor signed the order Monday because of what he calls “harsh winter conditions.” The order didn’t say what action would be taken for protesters who don’t comply, and a spokesman for Dalrymple didn’t immediately respond to calls and an email from The Associated Press.

The governor’s order says the unpermitted camp sites are not zoned for housing suitable for living in winter conditions.

Hundreds of people have been gathered at the encampment for months to oppose the four-state, $3.8 billion project, which they contend could affect drinking water and damage cultural sites. The Corps has ordered the protesters to leave federal land, but the Corps says it has no plans to forcibly remove anyone.