MOSCOW (Reuters) - International concerns over Iran's nuclear programme do not warrant any discussion at the moment of sanctions against Tehran, Russian Defense Minister Sergei Ivanov said on Friday. "I know of no instances in world practice and previous experience in which sanctions have achieved their aim and proved effective," Ivanov, shown on NTV television, told reporters in Russia's far east. "Moreover, I believe that the question is not so serious at the moment for the U.N. Security Council or the group of six to consider any introduction of sanctions. Russia stands for further political and diplomatic efforts to settle...