CANNON BALL, N.D. (AP) — Protesters trying to stop construction of the Dakota Access oil pipeline are bracing for a confrontation with police after the demonstrators refused to leave private land in the pipeline's path.

A months-long dispute over the four-state, $3.8 billion pipeline reached a crisis point when some 200 protesters set up camp on land owned by pipeline developer Energy Transfer Partners.

Law enforcement officers demanded that the protesters leave on Wednesday and they refused. It appeared that only thick fog and cloudy skies kept a large contingent of law enforcement officers from moving in. Officials have frequently monitored protesters by air.

Cass County Sheriff Paul Laney said Wednesday that the rule of law must be enforced.