The first coordinated US-Japan yen-buying intervention in 15 years has triggered a sharp rebound in the Japanese currency, squeezing bearish positions. However, analysts believe lasting gains will depend on the Bank of Japan backing the move with interest rate hikes, as the US-Japan yield gap remains the key driver of yen weakness.

Japan and the U.S. may unveil a joint policy next week to defend the yen after record interventions in April and May.

The U.S. joined Japan in buying yen, helping reverse the currency's slide as authorities signaled that further coordinated action remained possible.