Go behind police lines at the Dakota Access pipeline protests

Protesters aren't the only people camping out at the Dakota Access pipeline site in North Dakota. Police have been at a 5-acre camp north of protest encampments for four months.

Citing security, law enforcement officials won't say how many people they have working at the camp, but they estimate it has already cost nearly $15 million.

Sgt. Luke Hendrickson, with the North Dakota Highway Patrol, has been rotating in and out of the conflict for seven weeks, working with the Morton County Sheriff's Department and the North Dakota National Guard.

"You have to understand that as far as law enforcement is concerned, we're empathetic to both sides of this issue," he said. "We're kind of stuck in the middle trying to prevent anything that's happening that is unlawful, to keep one, the protesters from getting hurt, and to keep the interest of the private individuals, the private businesses to be moving as forward as well."

For the first time, officials let some journalists enter their camp to see how they work, where they sleep and what they eat.

Click on the audio player above to hear more.