BISMARCK, N.D. -- Neil Young is calling on U.S. President Barack Obama "to step in and end" what he calls the "violence" against protesters demonstrating against an oil pipeline being built in North Dakota near an Indian reservation.

In an open letter on Facebook posted Monday, the 71-year-old rock star calls the protest at the Standing Rock Indian Reservation "an awakening." He says demonstrators are "standing strong in the face of outrageous, unnecessary and violent aggression." He says law enforcement agencies and the National Guard are "seemingly acting to protect the interests of the Dakota Access Pipeline profiteers" with taxpayer money.

Young also chided President-elect Donald Trump, labeling him the "surprise president."

The letter is signed by Young and his girlfriend, actress Daryl Hannah.

Young included a video of him singing against the backdrop of the protest camp.