. >> john: weijia jiang is at the white house. weijia?reporter: well, president trump says canada and mexico must face those tariffs because they have failed to stop the flow of fentanyl into the u.s. and for this same reason, he is bumping up the fee on chinese imports. tonight, economists warn this could spark a trade war that will cost consumers. after following through on his threat... >> the tariffs, they're all set. they go into effect tomorrow. >> reporter: president trump says there's a simple solution for countries that want to avoid tariffs. >> what they have to do is build their car plants, frankly, and other things in the united states, in which case they have no tariffs. >> reporter: to make his point today, trump hosted the ceo of a taiwanese semiconductor chip manufacturing company who pledged to invest $100 billion in new manufacturing plants in the u.s. and the president said japanese automaker honda has ditched its plan to open a new plant in mexico, opting instead for indiana, to avoid tariffs. but auto prices are still