Tokyo's benchmark Nikkei Average plummeted more than 1,000 points. The index finished below the key 20,000-mark for the first time since September 2017.
Investors sold shares on worries that the global economy may be slowing down. The Nikkei Average tumbled 1,010 points, or five percent, to finish at 19,155. That's the lowest close in a year and 8 months.
Political turmoil in the Unites States also fueled the sell-off.
President Donald Trump tweeted that the Federal Reserve is the only problem that the US economy has. Trump stepped up attacks against the Fed after it raised the key interest rate for the 4th time this year.
And the partial shutdown of the government didn't help matters. That will last until the US Congress can agree on a spending bill. But many are worried that won't happen with Trump insisting on funding for a border wall.
