Such a tax would fly in the face of NAFTA and Canada and Mexico need to act maturely, calmly and resolutely if good sense doesn't prevail and the US actually imposes such a tax.

This entails Canada and Mexico each imposing their own BAT targeting US goods and not wait until (as we do with softwood lumber disputes) lengthy WHO proceeding have been concluded.

Clearly, all sides lose if matters proceed along this dismal tit-for-tat path but matters will be much worse for Mexico and Canada if a resolute response is not made.