Energy Transfer Partners says it’s ‘mobilizing drilling equipment’ to tunnel under Lake Oahe, which activists describe as ‘unconscionable and devastating’

The Dakota Access pipeline operator chose the day of the US presidential election to announce that the final phase of its controversial construction project will begin in two weeks – marking a bold escalation in its response to the Native American protests.

Dakota Access pipeline: the who, what and why of the Standing Rock protests Read more

Energy Transfer Partners, the company overseeing the North Dakota oil pipeline, has already completed construction up to the river that provides water to the Standing Rock Sioux tribe and announced on Tuesday it would soon begin drilling at the site.

The company said it would not halt construction, despite requests by federal agencies to delay the project as the US government reassesses permits and considers possible reroutes.

In a statement, Energy Transfer Partners said it was “mobilizing horizontal drilling equipment” in preparation for tunneling under Lake Oahe, a reservoir on the Missouri river by the protest camps and Native American reservation. The corporation said it would be ready to start crossing the water in two weeks.

The announcement came on a quiet election day at the encampments built by members of the Standing Rock Sioux nation and other indigenous people in opposition to the pipeline.

After a string of clashes and mass arrests, rumors spread among activists that the pipeline, government and tribal leaders had negotiated a 30-day moratorium on both construction and protest or religious ceremonies on the “front lines” of the conflict.

“I’m in shock. I’m speechless,” said Cheryl Angel, a Sicangu Lakota tribe member who has been at the Standing Rock camps since the spring. “It’s unconscionable and devastating. It’s almost as though they have no soul.”

The announcement presents the final phase of construction as a done deal, and will be seen as a clear illustration that the oil company is aggressively moving forward with the $3.7bn pipeline in defiance of Barack Obama and the thousands of demonstrators who are camped out at Standing Rock to fight the project.

Last week, Obama made his first remarks on the huge demonstrations since police arrested hundreds of unarmed protesters, who call themselves “water protectors” and say the pipeline is destroying sacred indigenous lands.

The president said the US army corps of engineers was exploring ways to “reroute” around Native American lands, and said the government was “going to let it play out for several more weeks, and determine whether or not this can be resolved in a way that I think is properly attentive to the traditions of the first Americans”.

In September, the government said it would temporarily halt permits to dig on federal land near or under the Missouri river and requested that the company “voluntarily pause all construction activity within 20 miles east or west” of Lake Oahe.

Energy Transfer Partners ignored that request and continued construction, recently approaching within a few miles of the river, causing widespread anger and sadness at the Standing Rock camps, which have been opposing the pipeline since April.

Tuesday’s statement does not address the requests from the government for a delay. On the contrary, it suggests that the company is not giving consideration to alternative routes or Obama’s recent remarks.

“Dakota Access previously received a permit from the army corps with respect the tunneling activities under Lake Oahe, and Dakota Access has all other regulatory approvals and land rights to complete the crossing of the Missouri river at Lake Oahe,” the statement said, adding that the company expects to receive final permissions “in a time frame that will not result in any significant delay”.

The army corps did not respond to requests for comment.

Asked about Obama’s comments, pipeline spokeswoman Vicki Granado told the Guardian: “We are not aware that any consideration is being given to a reroute, and we remain confident we will receive our easement in a timely fashion.”

The company’s announcement comes as North Dakota regulators are moving ahead with a formal complaint against the corporation for failing to properly disclose findings of Native American artifacts along the construction route.

Angel said the pipeline construction plan was “environmentally irresponsible” and “illegal” considering the army corps has yet to approve final permits. Noting that the Missouri river provided drinking water to millions, she added: “I’m in tears, because I can’t believe [the company] would do this to a whole group of people who don’t have any say.”

This past Sunday, more than a hundred water protectors used boats to ferry across the Cannonball river and attempted to climb “Turtle Island” – a portion of army corps land where tribal members say there are 11 burial sites. Several tribal elders, including Darrel Killsinsight, implored everyone to return to the main camp, referencing the alleged 30-day agreement.

But representatives of the tribe never officially confirmed that any such agreement was in place, and Tuesday’s statement flies in the face of any hope for a moratorium.

Jan Hasselman, the attorney representing the Standing Rock Sioux in its permit litigation, said that the statement from Dakota Access was probably a response to an army corps spokesman telling Bloomberg that the company had agreed to slow construction. But, she added, Dakota Access does not have all the permits it needs to begin drilling, including the easement.

“Starting construction without permits would be beyond the pale, even for Dakota Access,” Hasselman told the Guardian. “It is deeply irresponsible to keep putting investors’ money into this route when both the President and Senator Tim Kaine are openly discussing rerouting away from Lake Oahe.”

The timing of the announcement on election day instantly raised suspicion – and anger – among the activists gathered at Standing Rock. Activists have expressed frustration with the US presidential race, noting that Democratic candidate Hillary Clinton has refused to take a position on the conflict and GOP candidate Donald Trump has close financial ties to the pipeline.

“With the election being so big, and North Dakota being so small, they think they can just sweep this under the rug,” said Danny Grassrope, a member of the Lower Brule Sioux Tribe. “I’m not really surprised. Snakes are sneaky, and this is a black snake. It blindsides everyone.”

He added: “A lot of people are going to get angry, and this is where we need to stay positive. We need prayers more than ever now.”

The protesters were also disappointed that Obama has not condemned the highly militarized police force in North Dakota, which has arrested more than 400 people and deployed Mace, Tasers, rubber bullets and army tanks to respond to demonstrations.

A UN group is also investigating claims of inhumane jail treatment and other human rights abuses by law enforcement.

“Are indigenous people so invaluable that now that Dakota Access is to the water, does it not matter to anyone that people are going to start laying down their lives?” asked Eryn Wise, a member of the Jicarilla Apache and Laguna Pueblo tribes.

“I think that people need to seriously question the integrity of the work produced by DAPL right now, because they’re rushing,” Wise added. “Is it safe when they’ve been rushing like this?”

• The headline on this article was amended on 11 November 2016 to better reflect the article.