Bank of America Global Research discusses the latest wave of yen-buying intervention.

"As we argued previously a break above 160 would likely be interpreted as a sign of limited policy resolve, while successful intervention that pushes USD/JPY below 155 would have strengthened perceptions of strong commitment at least until recently.

The immediate focus is therefore the risk of USD/JPY moving above 160. Following the weaker-than-expected US July employment report released on 7 August, authorities had an opportunity to conduct a "follow-through" intervention and push USD/JPY below 155. Instead, no intervention materialized, and the pair has since traded back in the 159s," BofA notes.

"Confidence in Japan's commitment to defending the yen improved after coordinated intervention with the US on Jul 31. However, as USD/JPY has rebounded without any intervention over the past week, that credibility appears to have eroded," BofA adds.