President Donald Trump’s tariffs are hammering global markets this month, but plans for them have been in the works for years.

Elon Musk escalated his war of words with Trump trade adviser Peter Navarro on Tuesday, calling him "truly a moron" and "dumber than a sack of bricks" over comments about Musk's businesses. Why it matters: The gloves are off,

Musk, the billionaire Tesla CEO and close Trump ally, earlier this month called Navarro a "moron" after the trade adviser dismissed Musk's push for "zero tariffs" between the U.S. and Europe. Navarro had called Musk a "car assembler" reliant on imported auto parts.