Former Vice President Gore on Tuesday said “there’s no such thing as ethical oil,” slamming the notion that importing oil from U.S. ally Canada was better than doing so from unfriendly nations.

“There’s no such thing as ethical oil. There’s only dirty oil and dirtier oil,” Gore told Canada’s The Globe and Mail during a Tuesday event in Toronto.

Gore was responding to Globe and Mail Editor in Chief John Stackhouse on whether it made a difference that oil sands from the proposed Keystone XL pipeline would come from a democratic nation.

U.S. backers of the Canada-to-Texas pipeline have pointed out that the crude it carries would displace imports from less friendly nations, such as Venezuela.

The pipeline, which is at the center of an intense lobbying and political fight, is under federal review.