1307 GMT - The Japanese yen is failing to benefit from speculation about the Bank of Japan accelerating interest-rate rises as debt sustainability concerns persist, Societe Generale's Kit Juckes says in a note. Without fiscal policy tightening along with a sharp fall in oil prices and a narrowing of the gap between short- and long-term Japanese government bond yields, another test of policymakers' willingness to intervene and defend the yen seems inevitable, he says. Lower oil prices and upward revisions to Japanese growth forecasts could support the yen later this year "but we have to get out of the current U.S./Iranian impasse first." The dollar falls 0.1% to 159.19 yen after reaching a 12-day high of 159.54 Wednesday, LSEG data show.