Environmentalists and Native Americans have successfully interrupted the construction of a $3.7 billion energy pipeline, with local law enforcement voicing concerns about potential violence.

Construction was halted “for safety reasons,” the local Morton County sheriff said. “They were preparing to throw pipe bombs at our line, M80s, fireworks, things of that nature to disrupt us,” he elaborated in a news conference last week.

Sheriff Kyle Kirchmeier did not respond to my request for more information. Opponents of the pipeline have denied his claims, saying their protests have been peaceful.

Nonetheless, the delay of the pipeline, itself causes safety and security risks.

The line would transport oil underground for 1,154 miles, from North Dakota’s energy fields to Illinois.  Absent that pipeline, the highly flammable energy moves by train and truck, increasing the potential for accidents, including deadly ones like 2013’s Lac-Mégantic disaster, which left 47 dead.