Some of the explanations doing the rounds, not all of these are independent (at all) - i.e. intertwined

  • Potentially faster pace of U.S. rate hikes leading to risk aversion and thus flows to yen
  • Leveraged traders buying of USD/JPY after the fix, then bailed as despite their buying it didn't go up
  • Selling above 107.50 is option related (expiries later today) and will thus persist today
  • Higher U.S. yields put upward pressure on USD ... but offset by fall on US equity markets
  • Fed's minutes are pre equity market turmoil (meeting late Jan, stocks fell in in early February ... thus the Federal Reserve could have altered some of its views)
  • Rise in US. yields may not fully reflect concerns about the fiscal deficit, expanding debt supply ... weighs on stocks
  • USD/JPY selling will continue due to repatriation by Japanese companies ahead of fiscal year-end in March
  • Risk aversion wariness of more selling in stocks ... and thus further yen buying. Danger of this increases as US 10 yr approaches 3% yield
  • 3 Fed rate hikes this year already 'priced in', uncertainty on a 4th and thus weight on USD
  • USD/JPY near important technical support level, (circa 107.20) - raises near-term bearish attacks potential

And, this from the comments is good