When the original free trade agreements were negotiated the big attraction to the U.S. was Canada's guaranteeing access to our oil and gas.  This aspect of NAFTA can once again be used as the lever to convince the Americans of the benefits of NAFTA.  Why not levy tariffs on non-NAFTA imports of petroleum and petroleum?  This would give a boost to North American producers with minimal impacts on consumers.  It would prevent another submission to the whipsaw production and pricing whims of OPEC that threatened the entire North American oil and gas industry.  President Trump could label it a border tax and Prime Trudeau could label it a carbon tariff and use the proceeds to encourage non-hydrocarbon energy sources.