The pipeline will have to cross the Missouri River at some point.
And, if it must cross the river below the reservation, then it will have to go through the reservation. Currently, despite all the furore, it is not routed through reservation land.
Trump can resolve this issue immediately upon acceding to office. The appropriate permits will be issued. And any illegal protests will be handled appropriately.
The pipeline already crosses the Missouri in western ND. Now it has to cross back...