As President Obama’s decision on Keystone XL nears, opposition from Native American tribes — many of whom have long spoken out against the pipeline — is getting louder.

Last weekend, members of South Dakota’s Rosebud Sioux tribe set up a prayer camp near Mission, SD in protest of the Keystone XL pipeline. Tribe leaders say their plan is to send a message to the White House that Native Americans won’t back down on this pipeline, which they say would run through land guaranteed by an 1868 treaty for tribal use. The tribe members plan to keep the prayer camp up until President Obama denies the pipeline or until the pipeline is approved, in which case the camp will turn into a “blockade camp.”

“We’ve been talking about the XL Pipeline. Reading about it, discussing it, having meetings, and I think reality hit today,” Oglala Sioux President Bryan Brewer said at the camp’s opening ceremony Saturday. “This is the first day that we’re actually going to try to stop it.”

Tribe members have erected nine tipis, including one that will stay occupied 24 hours a day until the White House comes out with a decision on Keystone, and surrounded the camp with hay bales. The tribe is planning to enact three more prayer camps — also called spirit camps — near the proposed route of Keystone XL.