President Obama announced today that the State Department would not permit the construction of the Keystone XL pipeline, saying that the project’s completion would rob the U.S. of the moral authority to pressure other countries toward action on climate change.

“If we’re going to prevent large parts of this earth from becoming not only inhospitable but uninhabitable in our lifetimes, we’re going to have to keep some fossil fuels in the ground rather than burn them and release more dangerous pollution into the sky,” he said.

U.S. officials can’t prevent Canada from exporting the oil to China, however, which is one reason the State Department previously acknowledged that the construction of the pipeline would have a minimal effect on climate change. Obama made clear that he regards the decision as an important symbolic move, though.

“America is now a global leader when it comes to taking serious action to fight climate change,” he said. “And, frankly, approving this project would have undercut that global leadership.”

The announcement comes just days after the State Department denied a request from TransCanada, the company that wants to build the pipeline, to pause its review. Secretary of State John Kerry, in a separate statement, conceded that killing the Keystone pipeline would not “significantly impact” the amount of oil produced internationally. “The reality is that this decision could not be made solely on the numbers,” he said. “The United States cannot ask other nations to make tough choices to address climate change if we are unwilling to make them ourselves. Denying the Keystone XL pipeline is one of those tough choices — but it is the right decision, for America and the world.”

House speaker Paul Ryan described Obama’s decision as “sickening” in a brief statement. “By rejecting this pipeline, the president is rejecting tens of thousands of good-paying jobs. He is rejecting our largest trading partner and energy supplier,” Ryan said. “He is rejecting the will of the American people and a bipartisan majority of the Congress. If the president wants to spend the rest of his time in office catering to special interests, that’s his choice to make. But it’s just wrong.”

Obama’s announcement also angered some of the unions that typically receive favorable treatment from Democrats, and which stood to benefit from the jobs created by the pipeline’s construction. “The president may be celebrated by environmental extremists, but with this act, President Obama has also solidified a legacy as a pompous, pandering job killer,” Terry O’Sullivan, general president of the Laborers’ International Union of North America, said in a press release following the announcement.

— Joel Gehrke is a political reporter for National Review.