Environmentalists, Native American groups and landowners who've opposed Keystone expressed outrage, and Greenpeace said the U.S. was "moving backwards" on climate and energy policy.

Like the first three phases of the pipeline, the Keystone XL project drew heavy criticism from environmentalists, conservationists and Native American groups.

Keystone XL is an expansion of TransCanada’s existing system to funnel bitumen from Alberta’s oil sands to refineries on the US Gulf Coast.