The US dollar has hit a 14-year low against the Japanese yen with low interest rates in the US making the greenback less attractive to investors.
The dollar slipped to 86.5 yen, its lowest level since July 1995.
The US has indicated it is unconcerned about the dollar's slide, and will not intervene to strengthen it.
Many traders are swapping dollar holdings for gold as a safer investment in the current uncertain economic climate.
The price of gold is currently at a record high of $1,194.5 an ounce.
Close watch
"This yen strengthening is caused by dollar selling rather than yen buying, so this is not something Japan can handle itself," said Yutaka Miura at Mizuho Securities.
"This trend will continue unless the Japanese government takes action, in co-operation with the US."
In the short term at least, analysts said such intervention was unlikely.