TOKYO, Feb 18 : Oil prices fell slightly on Wednesday as talks between the United States and Iran progressed, raising hopes for a de-escalation of bilateral tensions and lowering risks of supply disruptions from the Middle Eastern oil producer. Brent futures dropped 3 cents or 0.04 per cent to $67.39 a barrel at 0139 GMT, while U.S. West Texas Intermediate (WTI) crude lost 5 cents or 0.08 per cent to trade at $62.28. Both are trading around two-week lows. Iran and the U.S. reached an