The new tariffs on imports from all three nations ‒ which are on top of existing tariffs ‒ went into effect Saturday.

Trump signs order with retaliation clause imposing aggressive tariffs on Canada, Mexico and China: Live - Further tariffs being considered for European Union and for energy, metals, pharmaceuticals, a

The move shows even China's "no limits" partners are "averse to becoming a dumping ground for Chinese excess capacity," one analyst said.