The regrettable escalation in force by both pipeline protesters and law enforcement Sunday evening underscored the urgent need for political leadership to forge a peaceful end to the standoff near North Dakota’s Standing Rock Sioux Reservation.

If North Dakota Gov. Jack Dalrymple is unwilling to lead, as this Editorial Board has previously called on him to do, then it’s time for President Obama to appoint an influential staffer or even Cabinet member to find compromise. Another violent clash between protesters and law enforcement Sunday, sparked by protesters trying to get closer to the pipeline construction, suggests that moment has arrived.

According to a Bismarck Tribune report, officers had rocks and burning logs thrown at them when they tried to stop protesters from removing burned-out vehicles blocking a road near the main protest encampment. Protesters told the paper that the vehicles were blocking the road for incoming emergency vehicles as well as outgoing protesters heading to a demonstration site closer to the pipeline. Law enforcement turned fire hoses, tear gas and beanbag rounds on protesters after orders to halt went unheeded. Seventeen people were taken to a hospital for injuries. An officer was also injured when struck by a rock.

Photos taken at the scene by Star Tribune photographer Rich Tsong-Taatarii provide jarring views of protesters facing down armored police vehicles. Sadly, this is but a precursor of violence to come if political leadership does not seek solutions. The new, oil-friendly Trump administration isn’t likely to continue the Obama policy of delaying approval of the pipeline’s Missouri River crossing. The Standing Rock tribe contends the pipeline threatens its water supply and that it goes through sacred ground.

The Obama delay raised hopes that the nearly complete pipeline can be blocked or moved. The president now needs to appoint a trusted adviser to bring all sides together to work toward a nonviolent resolution. This is a late addition to his agenda, but a must-do.