Italian President Sergio Mattarella said at Rouhani's first official engagement in Rome that the battle against Islamic State and fundamentalist extremists was "the number one threat facing the international community". Greeted by an honor guard at the president's Quirinale Palace, Rouhani smiled broadly for photographers before heading into a series of meetings. BUILDING TRUST Europe was Iran's largest trading partner before sanctions, with Italy and France seen as particularly close to Tehran. Both countries sent large trade delegations to Iran last year in the wake of the nuclear accord, laying the groundwork for tie-ups. Among the deals being readied for Italy was a pipeline contract worth between $4 billion and $5 billion for oil services group Saipem (MI: SPMI ), a source with knowledge of the matter said. Saipem was not immediately available for comment.