By Leika Kihara TOKYO (Reuters) – Japan likely won’t intervene in the currency market to defend a line-in-the-sand such as 145 yen versus the dollar, and instead limit any further action to smoothing operations aimed at taming volatility, former top currency diplomat Naoyuki Shinohara said. After the dollar’s spike to near 146 yen, Japan intervened in the currency market on Thursday to buy yen for the first time since 1998. Finance minister Shunichi Suzuki signalled readiness to step in again if yen moves become too volatile. Shinohara, who oversaw Tokyo’s currency policy during the Lehman cri…