Nomura Research discusses the scope for JPY intervention and notes that US-Japan FX cooperation is key to capping USD/JPY upside.

"Strong US CPI inflation and higher oil prices have boosted USD, pushing USD/JPY back to above 157.80. If Middle East tensions do not ease, the pair may continue to drift higher, but the 158 area is likely to attract increased caution around intervention," Nomura notes.

"Japan’s Finance Minister said Treasury Secretary Bessent confirmed close US-Japan cooperation on FX and financial market responses. This suggests US support for Japan’s intervention stance, which could limit further USD/JPY upside, though coordinated intervention still seems unlikely," Nomura adds.