Japan just spent billions to boost the flailing yen — and the US may get involved too

• Japan is reportedly using its dollar reserves to prop up the falling yen.
• The yen's depreciation is largely due to high US interest rates attracting investors.
• The US may step in to assist Japan, but the problem lies with the strong dollar.

Japan's yen has been on a sustained slide against the dollar, a slump that's great for foreign tourists looking for cheaper travel but could prove disastrous for its economy.

Now, it looks like Japan is tapping into its vast hoard of dollars to help the yen, which has fallen 13% against the greenback in the last year — and the US may get involved, too.