With only five weeks remaining for a basic agreement to be reached with Iran on the fate of its nuclear program , the world’s nuclear inspectors reported on Thursday that Iran was still refusing to answer their longstanding questions about suspected work on nuclear weapons and designs. The report, by the International Atomic Energy Agency , was issued just as an American negotiating team heads to Geneva for four days of talks that will, by Sunday, include Secretary of State John Kerry and his Iranian counterpart, Mohammad Javad Zarif. Most of those negotiations focus on the future, particularly on the question of how much nuclear fuel Iran would be permitted to produce and stockpile. But a lurking issue has been whether, as part of any final accord, Iran will be compelled to answer all questions that the I.A.E.A. has put to it about evidence of past work […]