President Obama said Tuesday that the controversial Keystone XL pipeline should only be approved if the project would not “significantly exacerbate” greenhouse gas pollution.

“Allowing the Keystone pipeline to be built requires a finding that doing so would be in our national interest,” Obama said during a speech at Georgetown University on his climate change plans.

“Our national interest will be served only if this project doesn’t significantly exacerbate the problem of carbon pollution,” Obama said. “The net effects of the pipeline’s impact on our climate will be absolutely critical to determining whether this project can go forward.”

The State Department already said in a March draft environmental review that the proposed Canada-to-Texas pipeline wouldn’t significantly boost greenhouse gas emissions, but the White House has thus far avoided weighing in on the pipeline.