USD/JPY was smashed lower to 147.40 after a break of 150.00.

So there you have it, they didn't want 150.00 to break.

USDJPY intervention
USDJPY intervention

I thought they might let it go above 150.00 because the dollar is broadly strong but it's clear now that the line in the sand is 150.00. However there has been a quick move to buy the break lower on the expectation that it's still clear sailing right up to 150.00.

Expect this pair to remain volatile as the market sorts it out.

I wouldn't expect any immediate confirmation of intervention but there's no other reasonable explanation.