WASHINGTON — Dealing a blow to former President Barack Obama’s legacy on climate change, President Donald Trump signed executive actions Tuesday to advance the construction of the Keystone XL and Dakota Access oil pipelines, a move cheered by congressional Republicans and decried by environmentalists.

Trump told reporters at the White House that the actions on the pipelines will be subject to the terms and conditions being negotiated by U.S. officials.

“From now on we are going to start making pipelines in the United States,” Trump said from the Oval Office.

Obama killed the proposed Keystone XL pipeline in late 2015, declaring it would have undercut U.S. efforts to clinch a global climate change deal that was a centerpiece of his environmental legacy. The pipeline would run from Canada to U.S. refineries in the Gulf Coast. A presidential permit is needed to approve the pipeline because it would cross the U.S border.

The Army decided last year to explore alternate routes for the Dakota pipeline after the Standing Rock Sioux tribe and its supporters said the pipeline threatened drinking water and Native American cultural sites.

The company developing the 1,200-mile pipeline, Texas-based Energy Transfer Partners, disputes that and says the pipeline will be safe.

The Dakota pipeline is set to carry North Dakota oil through South Dakota and Iowa to a shipping point in Illinois.

“Today’s news is a breath of fresh air, and proof that President Trump won’t let radical special-interest groups stand in the way of doing what’s best for American workers,” said Sen. John Cornyn of Texas, the second-ranking Republican in the Senate.

In July, the Army Corps of Engineers granted the company needed permits, but in September the agency said further analysis was needed.

On Dec. 4, the assistant army secretary for civil works, Jo-Ellen Darcy, declined to allow the pipeline to be built under Lake Oahe because she said alternate routes needed to be considered. Energy Transfer Partners called the decision politically motivated and said that Obama was delaying the matter until he left office.

Nearly 600 pipeline opponents have been arrested in North Dakota since last year. An encampment on Corps land along the pipeline route was home to thousands of protesters who call themselves “water protectors,” though the camp’s population has thinned due to harsh winter weather and a plea by Standing Rock Chairman Dave Archambault for the camp to disband.

Trump touted the stalled Keystone project during a late October campaign swing through Florida, saying: “We’re going to approve energy infrastructure projects like the Keystone pipeline and many more.” He listed the project among his top priorities for the first 100 days of his administration, saying it could provide “a lot of jobs, a lot of good things.”

Trump also supports the Dakota pipeline. Until last year, Trump owned a small amount of stock in Energy Transfer Partners and at least $100,000 in Phillips 66, an energy company that owns one-quarter of the pipeline. Trump sold the shares last year as part of a wide-ranging stock divestment, a spokesman said.

A spokesman said in December that Trump’s support for the Dakota project “has nothing to do with his personal investments and everything to do with promoting policies that benefit all Americans.”

Environmental groups blasted the order as a bid by Trump to serve the oil industry. Trump’s nominee for secretary of state, Rex Tillerson, is a former Exxon Mobil CEO, and his pick for energy secretary, former Texas Gov. Rick Perry, owns stock in Energy Transfers.

“Donald Trump has been in office for four days and he’s already proving to be the dangerous threat to our climate we feared he would be,” said Michael Brune, executive director of the Sierra Club.

He and other activists said the fight against the projects was not over.

“It’s a dark day for reason, but we will continue the fight,” said Bill McKibben, co-founder of the environmental group 350.org and a leader of a five-year fight against Keystone XL.

McKibben added: “People will mobilize again.”