The United States on Wednesday welcomed Iran's recent efforts to alleviate concerns about its nuclear programme, but urged it to increase the pace of cooperation. A recent report by the UN atomic watchdog IAEA found Iran was sticking to its agreements with the agency and implementing all newly agreed measures, even addressing matters related to bomb-making for the first time in six years. "You can't see steps taking place and say it's **t sufficient, those are good steps," the US delegate to the IAEA, Ambassador Joseph Macmanus, told journalists Wednesday on the sidelines of an IAEA board of gover**rs meeting. "This is a long stairway to climb and each step is progress." Addressing member states earlier, Macmanus however highlighted that Iran's engagement was "long overdue," according to a copy of his address.