President Obama’s secret weapon in the last days of nuclear negotiations with Iran is Energy Secretary Ernest Moniz, a nuclear physicist and the administration’s big brain in the talks. “To a large extent, it was a measure taken since the Iranians brought Salehi to the nuclear talks,” said Trita Parsi, president of the National Iranian-American Council. “Because the talks were getting so technical and so scientific … it would not have been beneficial if the Iranians had an ace like Salehi on their side, but the Americans did not have a strong counterpart on their side,” said Parsi, who has been traveling to Switzerland to track the talks.