Coordinated intervention
Reports that the New York Fed did “rate checks” (often interpreted as a potential prelude to intervention) plus Japan officials stressing coordination with the U.S. put the market on alert.
Previous examples
In March 2011, the G7 announced concerted intervention after extreme yen volatility following Japan’s earthquake.
What was happening in 2011?
Markets anticipated Japanese insurers and investors would bring money back to Japan to pay claims and fund rebuilding.
What’s happening now and why US wants a stronger yen now?
Excess volatility and disorderly FX moves can harm economic/financial stability
Japan’s finance minister has said the U.S. Treasury secretary shared concerns about “one-sided depreciation” of the yen, which signals the U.S. doesn’t want to be seen as tolerating a move that could be framed as giving Japan an unfair export boost.
A weak yen can worsen import-cost inflation and political stress in Japan.
Some exit from Japan might cause the temporary yen weakness (e.g. China selling).