They were expected to interfere, and they did indeed. Look at the 24h chart:
Yet the move is backfiring, again.
The Bank of Japan said it will keep interest rate at virtually zero until deflation has ended. The bank cut the overnight already ultra low rate target to a range of 0% to 0.1%. They will set up a 5 trillion yen ($60 billion) fund to buy government bonds and other assets, inflating the balance sheet.
Sounds familiar? Who gives me less for my currency?