The major currencies are off to an eventful start, and once again USD/JPY is drawing all of the attention. The pair fell nearly 1% in overnight trading, with a wave of selling arriving just before the US open in particular.

What is behind the decline in USD/JPY?

As noted early yesterday, a push above the 160.00 level is a dangerous game for the pair. The dynamic is largely psychological at the moment, and any attempt to run too far, too fast to the upside risks inviting intervention from Tokyo and/or Washington. Japanese authorities have repeatedly intervened in currency markets in recent years when rapid yen weakness emerged — most notably in 2022 and again during the sharp yen slide of 2024 — so traders are conditioned to treat big round numbers like 160.00 as potential trigger points for official action. There is also the possibility of rate checks from Tokyo, which would at least serve as fair warning to traders, and a signal of that kind may be amplifying the moves heading into the new day.

Beyond that, markets are growing more convinced of a Bank of Japan rate hike in September, while bond yields have pulled back somewhat from their highs. That eases some of the pressure on the yen and, for now, keeps the dollar's run-up in check. The interest rate differential between the US and Japan remains the core driver here: with Japanese rates still far below US rates, carry trades that sell the low-yielding yen have flourished, and any shift in BOJ policy expectations directly affects how attractive that trade remains.

So what is next for USD/JPY?

The pair has fallen back below the 158.00 mark to around 157.60, down 0.7% on the day.

On the big-picture chart, the decline not only eliminates support from the 200-day moving average (blue line) but also threatens the lows from 19-20 August near the 158.00 region itself. That puts sellers back in technical control of the pair and opens up scope for further downside, with the next daily support only seen closer to 157.00.

For now, traders appear to be heeding the warning of another potential intervention strike, but chasing a material break lower may prove difficult. First, traders have already fully priced in a BOJ rate hike this month. Second, it would take a significant downside surprise from tomorrow's US jobs report to trigger a material turnaround in the bond market — and even then, such a shift is not guaranteed to last.

As long as the bond market continues to feel the burn and yields stay elevated, the yen will remain under pressure. That holds so long as the US-Iran conflict also continues in its current state, with geopolitical tensions supporting safe-haven and rate dynamics that have kept US yields elevated.

In short, today's drop brings downside risks back into focus for USD/JPY as the pair takes out key technical support levels. However, several hurdles remain before such momentum can be sustained, the biggest of which is getting the bond market to play along. That said, it is clear that any major upside momentum is also now very limited by intervention risks — especially closer to 160.