It's much tougher for the Japanse Ministry of Finance to response to generalized US dollar moves than unique yen weakening.
That's why I don't think there will be immediate action taken on a break of 145.00, but my confidence in that assessment isn't high because we're dealing with unpredictable political decisions.
But if you look at EUR/JPY, it's down 400 pips in the past week. If you look at GBP/JPY, it's down 1000 pips in the past week. Even against, CAD, AUD, NZD and CHF, the yen has strengthened strongly in the past week.
So while USD/JPY is back to the important line in the sand, on a trade-weigthed basis, the yen is meaningfully higher than last time. I'm sure that MoF officials understand the futility of trying to fight broad USD strength, which is an monumentally larger challenge than fighting JPY weakness.
