Environmentalists opposed to the Keystone XL pipeline have requested that the US government turn over all documents related to the President黑料社檚 approval of the project.
As Canadian pipeline projects face a torrent of delays, there is an increased use in alternative transportation for oil in a bid to reduce the costs to the economy.
The 1078-mile pipeline will transport 33 billion m3 of natural gas from Turkmenistan to Afghanistan, Pakistan and India per year.