A Native American tribe in South Dakota has called a congressional vote to approve the Keystone XL pipeline an “act of war” and vowed to close the reservation’s borders if the US government tries to install a pipeline there.

The prospective route for the pipeline, which would connect Canadian tar sands fields to the Gulf coast, runs through the 922,759-acre (1,442 sq mi) Rosebud Sioux reservation in south-central South Dakota. The House of Representatives voted 252-161 on Friday to approve the pipeline.

“I pledge my life to stop these people from harming our children and our grandchildren and our way of life and our culture and our religion here,” the tribe president, Cyril Scott, said on Monday. He represents one of nine tribal governments in the state.



Scott said he will close the reservation’s borders if the government goes through with the deal, which is scheduled to come up for a Senate vote on Tuesday.

Environmentalists believe the pipeline would increase US reliance on fossil fuels and that the transport of tar sands oil across the United States could have serious environmental consequences. Campaigners for the pipeline argue that it would create more jobs and lower energy costs.

It is not clear whether President Barack Obama would veto the current legislation. The White House press secretary, Josh Earnest, said the president took a “dim view” of the bill. The administration has delayed making a decision about the pipeline and the State Department is currently reviewing litigation about a section of the pipeline route in Nebraska.

Scott said the creation of the pipeline would violate the 1868 Treaty of Fort Laramie, an agreement between the Sioux and the US government allocating parts of the Dakota territory to the Sioux. He also said he has not been consulted by the US government or TransCanada, the Canadian company behind the 1,700-mile pipeline.

“Did I declare war on our government? No I did not,” said Scott. “Did I declare war on the Keystone XL pipeline? Hell yeah I did.”

Several tribes in South Dakota have said they strongly oppose the pipeline, adopting tribal resolutions in opposition to the project. Some have also been providing training on civil disobedience tactics that could be used to stop construction of the pipeline, though details of those plans are being kept secret.

On Monday, Rosebud Sioux Tribe representatives were part of a group of campaigners who protested outside the Washington DC home of senator Mary Landrieu (D-Louisiana), a supporter of the pipeline. Scott said that he would be travelling to Washington DC this week and try to speak to politicians about why the pipeline should be stopped.

The House vote in favor of the pipeline came two days after the US and China announced that they had secretly negotiated a deal to reduce greenhouse gas emissions. The landmark deal was celebrated by environmentalists and the UN climate chief, Christiana Figueres, who said it provides momentum for a climate change agreement.