WASHINGTON -- The United States welcomed the publication on Wednesday of a final report by the United Nations' International Atomic Energy Agency, submitted to the Obama administration and in turn to Congress, that concludes Iran had "coordinated" an effort to develop nuclear explosive devices prior to the 2003 invasion of Iraq. The investigation found that much of Iran's nuclear weapons activities were in the research stage, and were not yet in development. The nuclear weaponization program largely ceased in 2003, the report asserts.As a part of the nuclear agreement reached in July with world powers, Iran was required to participate with the IAEA in its investigation into the possible military dimensions of its past nuclear work. The release of that report was scheduled for this month, and was a prerequisite for implementation of the deal itself."This IAEA report– which is an independent assessment based on facts– echoes our longstanding assessment about Iran’s pre-2003 weaponization work and its halt in 2003," a senior administration official told The Jerusalem Post on Wednesday."Far from giving Iran a pass on its past activities," the official said, "the IAEA’s Director General assesses that weaponization activities took place. This assessment enables us to work with the IAEA Board of Governors with a view toward closing the issue and focusing on fully implementing the JCPOA to ensure that no such activities happen again."Throughout two years of negotiations over Iran's nuclear program, the Obama administration insisted that Tehran participate meaningfully in the IAEA's investigation. But the White House also said the president did not seek a "confession" from Iran that it had, in fact, pursued atomic bombs. "Closing the PMD investigation will not preclude the IAEA in any way from investigating if the IAEA has reason to believe Iran is once again– in the future– pursuing covert nuclear activities, including nuclear weapons work," the official continued.The IAEA's board must now decide to what extent the agency will continue to examine whether Iran sought nuclear weapons in the past. Iran has said it will not uphold its side of the deal unless the matter is closed by the board."There's no smoking gun in there but we didn't expect one," one Vienna-based diplomat said of the report, but added: "Importantly, it's not a clear balance sheet for Iran."The report entitled "Final Assessment of Past and Present Outstanding Issues Regarding Iran's Nuclear Programme" said: "The Agency assesses that a range of activities relevant to the development of a nuclear explosive device were conducted in Iran prior to the end of 2003 as a coordinated effort."The year 2003 was when the IAEA confirmed that Iran had built a secret underground facility for enriching uranium.The report added the IAEA had "no credible indications of activities in Iran relevant to the development of a nuclear explosive device after 2009.""The Agency also assesses that these activities did not advance beyond feasibility and scientific studies, and the acquisition of certain relevant technical competences and capabilities," the IAEA said.Prime Minister Benjamin Netanyahu's office quickly responded to the report by issuing a statement that it proves “beyond any doubt that Iran's secret program for the development of nuclear weapons continued even after 2003, as Israel has maintained.” The report, the statement continued, exposed the methods Iran used to “conceal and deceive” the world regarding its nuclear program.“The most glaring example of this pertains to the Parchin facility where the Iranians tried to hide and tamper with evidence of their illicit activities,” the statement read. “Israel expects the international community to continue and expand the IAEA investigation in these areas and to use all means at its disposal to ensure that Iran will not be able to secretly build a nuclear weapon. Unless and until the investigation is completed, the world will not know the full extent of Iran's covert nuclear weapons program and where it stands today.”Reuters contributed to this report.