Iran will start unlimited nuclear research and development work on Friday as part of its third phase of cutting down commitments under the 2015 nuclear deal. Tehran announced the decision on Wednesday, saying it would begin developing centrifuges to speed up the enrichment of uranium, which can produce fuel for nuclear power plants or atomic bombs. However, it denies seeking nuclear weapons and says it still wants to save the nuclear agreement. It has given Europe a new 60-day deadline to salvage the pact. Iran's Foreign Minister Mohammad Javad Zarif has defended his country's decision, saying it was a response to American sanctions.