The US currency slumped two percent against the euro and hit a decade low against the safe-haven Swiss franc, while Brent North Sea crude and the main US oil contract WTI tumbled more than five percent on fears the tariffs could spark a trade war that hits economies worldwide.
Dollar hits lowest since January 2015 vs Swiss franc, last down 3.31% at 0.8290 franc.
The euro rose 2.27% to 1.11988 against the U.S. dollar, while the greenback fell 2.12% to 144.235 against the Japanese yen.
Crude oil May futures declined 3.66% to $60.07 as investors assessed concerns over trade war amid the shifting US policy. West Texas Intermediate plunged to trade below $60 a barrel, once again sitting near a four-year low.