President Donald Trump signed executive orders on Tuesday to push forward the Keystone XL and Dakota Access pipelines, opening new fronts in his looming war with environmentalists.

Keystone was rejected in 2015 by former President Barack Obama after a seven-year review. Trumps orders clear the way to continue building Energy Transfer Partners 1,172-mile Dakota Access project, which has been stalled since the U.S. Army Corps of Engineers halted construction in December amid massive protests led by the Standing Rock Sioux.

This is with regard to the construction of the Keystone pipeline, something that has been in dispute, and subject to a renegotiation of terms by us, Trump said of the first action during a signing broadcast on TV networks Tuesday morning. Were going to renegotiate some of the terms and if they would like, we will see if we can get that pipeline built. A lot of jobs, 28,000 jobs. Great construction jobs.

Trump then signed the second action.

This is with respect to the construction of the Dakota Access Pipeline, he said, introducing the leather-bound order. Again, subject to terms and conditions to be negotiated by us.

Another action signed Tuesday calls for U.S. steel to be used if the pipelines are built, though that may mean little in the case of the Dakota Access Pipeline, which is nearly complete. One more order aims to overhaul what Trump called the horrible permitting process by slashing environmental regulations.

If were going to build pipelines in the United States, the pipelines should be built in the United States, Trump said. Were going to put a lot of workers, a lot of steelworkers back to work. We will build our own pipes, we will build our own pipelines, like we used to in the old days.

The moves mark the first serious step by the new president to reverse his predecessors environmental gains in favor of propping up an oil and gas industry dogged by low prices, competition from renewable energy and regulations aimed at cutting carbon emissions. Republicans, who pushed Obama to greenlight both pipelines, hailed the orders as a victory.

The unfortunate reality is that these important infrastructure projects were used by special interests to advance their radical anti-energy agenda and were therefore needlessly halted by the last administrationto the detriment of Americas national interest, House Speaker Paul Ryan (R-Wis.) said. These pipelines will strengthen our nations energy supply and help keep energy costs low for American families.

The day after Trumps surprise election victory, TransCanada, the company behind the Keystone XL, announced plans to meet with the incoming administration to once again pitch the proposed 1,179-mile oil conduit from Alberta to Nebraska. The firm said Tuesday it was preparing an application to submit.

Trump said in May he would support the Keystone pipeline if the U.S. government could get a share of its revenue, which may not be legal. But Trumps vow to renegotiate the 1993 North American Free Trade Agreement, on which he plans to sign an executive order this week, could complicate things. In June, TransCanada sued the U.S. government through a legal clause in NAFTA.

Still, Keystone XL may prove easier than the Dakota Access Pipeline to build the State Department handles large parts of the permitting process because the conduit crosses a border, Daniel Riesel, senior partner at the environmental law firm Sive, Paget & Riesel, told The Huffington Post.

The pipeline would largely pump oil from tar sands a noxious mix of sand, clay and bitumen, a thick, viscous oil to refineries on the Gulf coast of Texas. Keystone XL would carry 830,000 barrels of tar sand oil, considered one of the dirtiest fossil fuels, into the U.S. daily, producing emissions equivalent to putting 5.6 million new cars on the road, according to estimates by the environmental nonprofit Friends of the Earth.