American president Barack Obama has decided not to approve the construction of the Keystone XL oil pipeline, The Washington Post reports.

The $7 billion project would have linked up the oilfields of Alberta, Canada with refineries and ports on the Gulf of Mexico in Texas and transferred the equivalent of 800,000 barrels of oil per day.

It took Obama, who is due to step down next year, virtually all his presidency to reject Keystone.

Late last year — after his State Department had, unusually, reviewed the pipeline application twice already — the president insisted he wanted to let an “independent process” play out before making a decision.

Except there was no more process going on. All that had been left to do since March 2013, when the second State Department study reiterated the first’s conclusion that building or not building Keystone would have made no difference for the environment, was for the president to make up his mind.

The real issue wasn’t the environment. The State Department said that “approval or denial of the proposed project is unlikely to have a substantial impact on the rate of development in the oil sands or on the amount of heavy crude oil refined in the Gulf Coast area.” It also suggested, in 2013, that if Keystone wasn’t built, Canada would find other ways to get its oil to market.

The following year, it did. Exasperated by Obama’s indecision, the Canadian government approved the construction of an alternative pipeline that will transport some 525,000 barrels of oil per day from Alberta to the Pacific coast — from where it can be exported to China.

The real issue was political. The president’s Democratic Party was divided: trade unions wanted Keystone built because it would have generated jobs; environmentalists rejected the obvious and insisted that building Keystone would encourage Canada to extract more oil.

Oil sands pollute more than conventional oil wells but Canada wasn’t going to change its energy policy because of a decision made in Washington DC. If, after ousting pro-oil prime minister Stephen Harper last month, Canada scales back its Alberta tar sands, it will be its own choice, not America’s.

97 percent of Canadian oil exports now go to the United States which is also its biggest trading partner. Barring a change in policy under incoming prime minister Justin Trudeau’s administration, Alberta’s daily oil production of 1.5 million barrels is set to double over the next fifteen years.