In a cautious first step toward unlocking 30 years of tense relations, senior US diplomat Richard Holbrooke had a brief but cordial meeting with Iran's Deputy Foreign Minister Mehdi Akhundzadeh Tuesday at an international conference on Afghanistan. The rare diplomatic approach was the first official face-to-face interplay between the Obama administration and the Iranian regime. US Secretary of State Hillary Rodham Clinton cautioned that the talks were promising but not “substantive.” “They agreed to stay in touch,” Clinton said at the close of a one-day conference on Afghan security and development that was designed partly to allow the diplomatic turn with Iran. The meeting came on the sidelines of a session aimed at improving Afghanistan's future prospects. Akhoundzadeh told the meeting that Tehran was ready to help both in fighting Afghanistan's huge opium trade and in reconstruction of the impoverished state. Clinton described the gesture as promising. Akhundzadeh, however, criticized US plans to send more troops into Afghanistan. AP, Reuters __