Last week, the Cheyenne River Sioux Tribe told TransCanada "We will be waiting" in a response to a letter notifying them of impending construction on the Keystone XL Pipeline on historic, territorial lands.
On Tuesday, the Rosebud Sioux Tribe reaffirmed they stand with their neighbors to the north.
Announcing his tribe's "unified opposition" against TransCanada, President William R. "Willie" Kindle said in a statement that the tribe will protect treaty rights, sacred sites and the Oglala Aquifer.
"The proposed construction corridor for the Keystone XL Pipeline crosses the historical treaty territory boundaries of the Rosebud Sioux Tribe," the statement said.
In a letter sent to CRST last week, TransCanada's Senior Manager of Indigenous Relations, Nadine Busmann, acknowledged the "distinct relationship to the land" shared by the tribes.
The Alberta-based energy company will begin moving construction-related materials later this summer into the fall, she said. Keystone XL received approval from a Nebraska commission late last year to begin its long-anticipated project to connect the northern oil fields to an Illinois refinery.