India, Feb. 8 -- President Trump needs to study the Friend or Foe systems.

In times of war, aircraft identification systems are used by ground controllers to distinguish friend from foe, and it is obvious that the response would be very different in the two cases. President Trump needs to study such Friend or Foe systems, as his initial imposition of tariffs on Canada, Mexico and not just China, did not appear to make enough distinction between the first two and the third. Mexico and Canada are allies of the US, China an adversary. The additional tariffs levied only on China would not affect market confidence across the world in the way that tariffs on two friendly countries, Mexico and Canada had while they lasted. Unless carefully thou...