President Donald Trump signed executive actions Tuesday morning to advance the Keystone XL and Dakota Pipelines, NBC News confirms.

The decision is sure to anger environmental advocates who say that the projects would have severe negative impacts on the areas where they are built and would encourage more reliance on fossil fuels. The Standing Rock Sioux tribe and its allies have vigorously protested the Dakota Access project, saying it would damage cultural sites.

Background: Reprieve for Native tribes, Army denies Dakota pipeline permit

In a statement, Greenpeace executive director Annie Leonard pledged that the same group of environmentalists, Native American activists and farmers that successfully stalled the projects in the past will continue to fight their advancement.

"Keystone, the Dakota Access Pipeline, and fossil fuel infrastructure projects like them will only make billionaires richer and make the rest of us suffer," she said. "We will resist this with all of our power and we will continue to build the future the world wants to see."

Backers of the pipelines say they will create jobs and cut energy costs.

During a meeting with auto executives earlier Tuesday, Trump described himself as "an environmentalist" but argued that federal regulatory and permitting processes are too drawn out.

"I am, to a large extent, an environmentalist," he said. "I believe in it, but it's out of control and we're going to make a very short process and we're going to either give you your permits or we're not going to give you your permits, but you're going to know very quickly."

The Obama administration rejected the Keystone XL pipeline in November 2015, and it denied a permit for the Dakota Access project late last year.

Related: 10 promises Trump made for his first day