Amano notes that much of the staff involved in that probe will be foregoing Christmas and New Year holidays in order to probe, which has already had to seek out additional voluntary funding on two previous occasions. A portion of the increased workload is no doubt attributable to Iranian resistance to the probe, which has been manifested through denial of access to certain suspicious sites and failure to follow through on promises to provide information explaining past activities that could be connected to research into detonation of a nuclear weapon.

Rappler adds that the IAEA further commented upon Iran’s efforts to control the probe on Thursday. Organization spokesperson Serge Gas told reporters that it had made clear to Iranian officials that their offer of one limited inspection of a research and development site in Marivan is not sufficient to answer IAEA concerns.

As previously reported, the Marivan visit has been offered as an alternative to inspectors’ requests for access to the Parchin military base that is suspected of having done some work on nuclear detonation. Although the IAEA also suspects that relevant tests were conducted at Marivan, the Iranian regime has insisted upon control over inspections, leaving open the possibility for significant concealment. Furthermore, as Gas emphasized, even unconstrained Marivan visits would not answer broader questions about Iran’s network of nuclear and military research operations.

Meanwhile, Iran has attempted to shift the burden of proof for accusations concerning that research. The country’s envoy to the IAEA, Reza Najafi, insisted that the sources of intelligence about those activities must “provide the details to the agency, to enable the agency to verify their claims,” which Iranian officials declared to be baseless. But a 2011 report by the IAEA already judged the relevant intelligence to be “broadly credible.”

Among opponents of the Iranian regime, its lack of cooperation with UN inspectors renews concerns about the possibility of the regime pursuing nuclear research that it is concealing from the view of inspectors even in the midst of the probe. In other words, such secrecy potentially undermines the intentions of the Joint Plan of Action, which secured some limits on Iran’s enrichment and research activities as a condition of opening negotiations between it and the P5+1 concerning the nation’s nuclear program and the international sanctions aimed at curtailing it.

In an editorial at National Interest, Jofi Joseph, former US National Security Council Director for Nonproliferation, argues that the JPOA has been successful in preventing the further expansion and development of the Iranian nuclear program. He further argues that many of the worries about that agreement being favorable to Iran are misguided or misinformed. However, Jofi does not acknowledge concerns over the possibility of “sneak-out” through secretive work, as opposed to “break-out” via development that is permitted under the JPOA.

Jofi also claims that the seven month extension of nuclear negotiations, which was signed last month, secured new concessions from Iran that will further limit its capacity for conspicuous development. But reports of these concessions, including agreement to some snap inspections and further conversion of uranium oxide, have come only from the United States. The Obama administration has previously been judged to have lied about the status of negotiations and private agreements, and in fact Iranian officials have explicitly denied the US claims regarding these supposed new concessions.