Top Iranian figure Akbar Hashemi Rafsanjani said Iran's decision to resume sensitive nuclear work was "irreversible" and warned that Western opposition to Iran's program will "cost them dearly". During a Friday sermon, the prominent ayatollah said: "You could drag things on but Iran's decision is irreversible," drawing chants of "Death to America" and "Death to Israel" from the faithful. The influential former president warned worshippers not to "take lightly what happened at the IAEA. It is very important and will create new conditions for our country and the region. It will turn a new leaf in the history of our revolution. "It will cost them dearly," he vowed, signaling the possibility of a hardened stance by a country that plays an important role in Iraq, Afghanistan and the Gulf as well as being a major oil producer. "Bear in mind that you cannot treat Iran like Iraq or Libya," added Rafsanjani, who heads Iran's top arbitration body, the Expediency Council.