TOLUCA, Mexico (AP) -- President Barack Obama is defending the lengthy process the U.S. is using to decide whether to approve the Keystone XL pipeline.
Canada has been pushing the U.S. for years to approve the pipeline, which would carry oil from Canada's tar sands to the Texas Gulf Coast. Environmental groups oppose it and Obama has said he won't approve it if it increases greenhouse gas emissions.
Obama says all nations must take emissions into account in making decisions. He says climate change science is irrefutable.
Obama spoke at a joint news conference with Canadian Prime Minister Stephen Harper and Mexican President Enrique Pena Nieto.
Harper says the U.S. State Department's review was definitive in determining the pipeline won't increase emissions. He says his views that the pipeline should be built are well-known.