 -- The Standing Rock Sioux Tribe has joined a motion filed Thursday by the Cheyenne River Sioux Tribe seeking a temporary restraining order to stop construction of the final section of the Dakota Access Pipeline, which began earlier this week.

In a declaration filed with the motion, Standing Rock Sioux Tribal Chairman Dave Archambault, II, writes that it is "vitally important to our people that our rights be heard by this Court before Dakota Access drills under Lake Oahe."

He writes of the "terrible misdeeds and abuse" the Tribe has suffered in its dealings with the federal government," a pattern he says "continued with respect to the Dakota Access pipeline," until the Army, in the waning says of the Obama administration, determined that the tribe's concerns had merit and ordered an environmental impact statement that would explore alternative routes for the pipeline.

"That step suggested, perhaps for the first time ever, that the voices of the Tribe do matter and that the federal government was willing to at least consider, in a meaningful way, our rights," Archambault wrote. "The decision ... signified a recognition that we have a right to be heard."

On Wednesday, however, the Army Corps of Engineers granted an easement to the developer of the four-state crude oil project, allowing it to install the last stretch of the 1,172-mile pipeline. Part of this 1.25-mile section will run under Lake Oahe, just upstream of the Standing Rock Sioux Tribe reservation. The Army also cancelled the environmental impact review.

The tribe's attorney, Jan Hasselman, told ABC News that the Corps' decision to grant the easement was a "bow to political pressure."

Whatever the names are on the lawsuit, Hasselman said, "this is about Trump's reversal of an action meant to protect the tribe."

President Trump signed a presidential memorandum aimed at advancing approval of the pipeline, on January 24th, declaring that its completion was in the national interest.

"I don't even think it was controversial," President Trump said of his decision during informal remarks at the White House earlier this week. He made no mention of the months of protests and legal challenges that have surrounded the pipeline project.

"I haven't had one call. Usually if I do something, it's like bedlam. I haven't had one call, from anybody," the president said. "I think everybody is going to be happy in the end."

But Archambault says in the new court filing, that the decision show the federal government is once again breaking promises and ignoring interests of Indigenous people, and he is asking the Court to step in.

"Having come this far, there will be a deep and harmful impact on us if we are told that, not only has the Army changed its mind, but that the Court will not hear us until after the drilling is done and the oil is flowing," Archambault writes. "If that happens, it would reinforce the deeply held understanding that the historic wrongs committed by the United States against us will continue and that our voices will not be heard in ways that matter by those who have the power to stop the harm to our people."

The Cheyenne River Sioux Tribe, which had previously joined the Standing Rock Sioux Tribe’s lawsuit against the pipeline, filed a motion Thursday morning at the U.S. District Court for the District of Columbia seeking a temporary restraining order "to halt construction and drilling" under and on either side of the land surrounding Lake Oahe. The tribe argued that the pipeline "will desecrate the waters upon which Cheyenne River Sioux tribal members rely for their most important religious practices and therefore substantially burden the free exercise of their religion," according to court documents obtained by ABC News.

The Cheyenne River Sioux Tribe, which is part of the Great Sioux Nation, requested that the judge immediately issue a temporary restraining order to stop construction, with a hearing to be held at the court’s earliest convenience.

The Cheyenne River Sioux Tribe filed a separate motion seeking a preliminary injunction directing the Army Corps to withdraw the easement issued to the pipeline company Wednesday. The tribe alleges that the easement granted is “entirely unlawful” under the Religious Freedom Restoration Act, according to the court documents.

The joint motion from the tribes is scheduled to be heard Monday at 2 p.m. ET.