The Obama administration is attempting to clarify a key position in its nuclear negotiations with Iran amid suggestions in media reports that the US has made a consequential concession this week.In remarks to the State Department press corps via teleconference on Tuesday, US Secretary of State John Kerry said the world already knows the nature of Iran's past military nuclear work— and that negotiators were not "fixated" on forcing Tehran to reveal its activities from a particular moment in time.The comment was widely interpreted as a departure from past statements made by key administration officials over several years. Both he and US President Barack Obama have said that Iran must "come clean" in any final agreement on all of its past experimentation with nuclear weaponry, referred to formally as Possible Military Dimensions (PMD). At the top of his first briefing as State Department spokesman, John Kirby said the US is not looking for a "confession" from Iran. But the US never has, he continued, and is making no concession on the PMD issue."The [International Atomic Energy Agency]'s concerns about possible military dimensions, past and present, have to be resolved before there is a deal," Kirby told the press, charging that it is "absolutely, completely false" that the US had shifted on the matter.The IAEA has sought access for its investigation into Iranian PMD for several years. That, in part, requires access to sites categorized as military installations by the Islamic Republic.Iran says it will reject all requests for access to its military sites, citing its need to protect "state secrets" and its sovereignty as a UN-member state. "Sanctions lifting is only going to occur when those steps have been taken," Kirby asserted.Phasing of sanctions relief is a major, outstanding challenge left for negotiators to resolve since a framework for a nuclear deal was agreed upon in Lausanne, Switzerland, back on April 2. Reporters and interests surrounding the Iran talks have been unclear on whether a resolution to the PMD issue would precede a deal itself, or would rather precede sanctions relief.Further complicating the issue is whether a full resolution to the IAEA's concerns would precede all sanctions relief, or merely some."It is very clear what the expectations are of Iran," Kirby asserted, noting that the issue has figured "prominently" in the final round of negotiations.Diplomats from the US, Russia, China, France, Britain, Germany and Iran hope to clinch a comprehensive nuclear agreement by June 30.Patrick Clawson, Director for Research at the Washington Institute for Near East Policy, called the development a "clear cut case of moving the goal posts.""It is discouraging for the USG to suggest that a political process, such as the Iran-P5+1 talks, will substitute for the judgment of the IAEA," Clawson said in an e-mail. "The IAEA should be allowed to do its work without diplomats undercutting its authority. Technical issues about verification should not be decided in a political venue." In recent months, members of the Obama administration have justified their pursuit of a full resolution of IAEA concerns with a simple argument: Only by fully accounting for their past nuclear work can the international community truly hold to account Iran's future nuclear work.In the same press availability on Wednesday, Kerry said that access to these sites was "very, very critical" in any final deal."The [interim Joint Plan of Action] refers to that, and says that it’s got to be addressed in the context of the final product," Kerry said. "And that remains true; it has to be. And we have to resolve our questions about it with specificity."Talks continued in Vienna on Thursday, and are expected to continue on a daily basis until the deadline.US ambassador to Israel Dan Shapiro said Wednesday that if Iran insists that there not be inspections at all its nuclear facilities then “there will not be an agreement.”Likewise, he said that if Iran “does not give information on its past military nuclear plans, then there will not be an agreement. If Iran demands relief from all sanctions from the first day, there there will not be an agreement,” he said in an Army Radio interview.“We also have demands,” he said, “and will only accept a good agreement, and if there will not be a good agreement, there will not be an agreement.”Herb Keinon contributed to this report from Jerusalem.