US President Donald Trump has announced new import taxes of 25% on cars and car parts coming into the US.
Tariffs for businesses importing vehicles to begin tomorrow. Tariffs for parts are set to begin in May or later.
The president claimed the move would lead to tremendous growth for the auto industry, promising to boost jobs and investment in the US.
The US imported roughly eight million cars last year, accounting for around $240 billion (£186 billion) in trade and roughly half of overall sales.
Mexico is the top foreign supplier of cars to the US, followed by South Korea, Japan, Canada and Germany. Trump's latest move is expected to bring upheaval to global auto trade and supply chains.
The White House said the order would apply not only to finished cars but also to car parts, which are often shipped from other countries before being assembled in the US.
However, the new tariffs on parts from Canada and Mexico are exempt.
Japanese Prime Minister Shigeru Ishiba said his government would put "all options on the table" in response to the tariffs.