The trade war is here.

U.S. tariffs have gone into force, affecting $34 billion of Chinese products. Beijing plans retaliation in kind, and American metal producers, energy companies and automakers are worried. Some businesses are bracing by halting hiring, putting off expenses and otherwise cutting costs.
The dispute is expected to ripple through global supply chains. Global stock markets have been volatile in anticipation of a trade fight between the U.S. and almost everyone else.