Moving quickly to try to erase Barack Obama’s environmental legacy, President Donald Trump signed an executive order this morning to move forward with the Keystone XL and Dakota Access oil pipelines. Keystone XL is the planned 1,200-mile-long pipeline that would carry 800,000 gallons of crude oil a day from the Canadian tar sands fields in Alberta to refineries in Texas. Dakota Access would stretch from North Dakota to Illinois and carry petroleum from the Bakken oil fields. It would cross beneath the Missouri River in North Dakota, the water source for the nearby Standing Rock Sioux reservation, which sparked fierce opposition from the tribe and its many Native American and environmental allies last fall.

“The Keystone pipeline was rejected because it was not in the country’s interest, and the environmental review of the Dakota Access Pipeline was ordered because of the threats it poses to the Standing Rock Sioux,” said Sierra Club executive director Michael Brune. “Nothing has changed. These pipelines were a bad idea then, and they’re a bad idea now.”

In terms of Keystone XL, Trump’s order “invites TransCanada [the pipeline’s builder] to resubmit its proposal and directs agencies to approve it without delay,” according to White House spokesperson Sean Spicer. In 2015, the State Department concluded that the project was not in the national interest. In regard to the Dakota Access Pipeline, the executive order is expected to rescind the environmental impact statement process ordered by then-president Obama that would explore new routes for the pipeline. That process was upheld in federal district court only last week after a judge rejected a request by attorneys for Energy Transfer Partners, the company building the pipeline, to put a temporary restraining order on the environmental review process. Trump at one time held stock in Energy Transfer Partners. His spokesperson has stated that he sold the stock, although no proof has yet been offered.

Environmentalists and Native American tribes vowed they would continue their opposition to both projects, which they say are incompatible with the need to reduce greenhouse gas emissions. The Standing Rock Sioux immediately declared that it would take legal action to try to block Trump’s order. “We will fight this with whatever we have, in the courts and in the streets,” said 350.org’s Bill McKibben.

“Anybody who saw and witnessed the first KXL project knows how much ranchers are opposed,” said Jane Kleeb of Bold Alliance, the Nebraska-based network of pipeline opponents. “We have an alliance with the tribes—the Cowboy and Indian Alliance—and Donald Trump is up for a big fight if he thinks he’s going to get any foreign steel and foreign oil through the Nebraska plains and the Ogallala Aquifer.” Kleeb said it would be very difficult for TransCanada to use eminent domain to clear the pipeline right of way since eminent domain requires that projects be in the public interest, a standard she said the project does not meet.

The fate of the Keystone XL Pipeline may rest on politics north of the border. When the project was first conceived, a stalwart fossil fuel ally, Stephen Harper, was prime minister of Canada. In 2015, Harper lost a reelection bid; the current prime minister, Justin Trudeau, is more of an environmentalist. His government signed the Paris climate accord and also banned offshore oil drilling in the Arctic Ocean. A new government in the province of Alberta is also moving to cut greenhouse gases by, among other things, moving to put a price on carbon.

“The Canadian public is widely opposed to any increase in pipeline capacity and anything that would compromise our emissions-reductions promises,” said Tim Gray, executive director of Environmental Defence in Canada. “They [TransCanada] will have a hard time attracting the capital necessary for the pipeline to be built.”