It’s a battle of political leverage. Who can use tariffs, retaliatory tariffs or sanctions to create more political pain for the other leader. Forcing them to capitulate or face undesired consequences.

How crazy would it be if China, Mexico and/or Canada initiated tariffs before Trump took office

From your standpoint as a businessman and manufacturer, is there any sense behind this? Especially now that other countries are threatening tariffs of their own in retaliation. But that doesn't make sense cause it would mean raising their own taxes.