NAFTA doesn't cover new supplies. The Keystone project would have carried new production (that G.W.Bush asked for). It also doesn't prevent the U.S. from buying less oil — even completely boycotting all oil-sands oil, as many are calling for. If the U.S. ever cuts back on imports of Canadian energy; Canada is under no obligation to ever return exports to previous levels.
Oil is a fungible commodity — but, a supply coming by pipeline from a friendly country is more secure than oil from the Mideast or Venezuela.
There ya go again.....clouding the issue with facts, common sense and logic!