It turns up the heat in an increasingly bitter trade war between the US and its biggest trading partner.
The 25% duties apply to Chinese machinery, electronics and other high-tech equipment including cars, computer hard drives and LEDs.
Beijing is expected to take retaliatory measures after saying it had no choice but to fight back.
It may be some time before the effect of the tariffs is clear.
It will take three, six or 12 months before their impact becomes visible, Tokyo branch manager for State Street Bank and Trust, Bart Wakabayashi, said.
News Source SkyNews