WASHINGTON -- No deal emerged from talks this week to open the door for a U.N. probe into allegations of nuclear-weapon activities in Iran, the International Atomic Energy Agency's top delegate to the session said on Friday.
"We had two days of intensive discussions" in Tehran, IAEA safeguards chief Herman Nackaerts said in a statement to reporters after returning to Vienna, Austria. "Differences remain, so we could not finalize the structured approach to resolve the outstanding issues regarding possible military dimensions of Iran's nuclear program."
The U.N. organization agreed to resume talks on Feb. 12 with Iran, which insists its atomic activities are strictly peaceful.
The meeting that ended on Thursday marked the latest in a series of attempts over the past year to establish ground rules for the nuclear watchdog to investigate intelligence indications that Iran has carried out experiments relevant to nuclear weapons development. Agency officials have resisted Iran's demand for documentation forming the basis of suspicions largely outlined in a November 2011 report, as well as Tehran's call to limit their investigation to predefined questions they could not revisit once answered.
After meeting with Iranian officials in December, Nackaerts said his team had achieved progress and voiced hope that the January discussions would lead to an agreement. Agency Director General Yukiya Amano, though, last week voiced doubt that the sides would eliminate remaining differences.
One issue analyst tied Tehran's intentions at this week's meeting to efforts by six nations to arrange a separate set of multilateral discussions aimed at defusing the nuclear standoff. Iran joined three such meetings last year with counterparts from China, France, Germany, Russia, the United Kingdom and the United States.
"Any deal that the P-5+1 makes with Iran is going to have to be based upon an understanding about how the agency will go about its job of verifying Iran’s nuclear activity," said Carnegie Endowment for International Peace nuclear expert Mark Hibbs.
The Obama administration on Friday criticized the Persian Gulf regional power over the failure to reach an agreement.
"We’re obviously deeply disappointed that Iran has once again missed an opportunity to cooperate with the IAEA and to provide the international community with the transparency that we’re all seeking in order to resolve our concerns about Iran’s nuclear program," State Department spokeswoman Victoria Nuland told reporters.
Nackaerts said Iranian officials had again denied his agency access to the Parchin military installation, which Tehran had placed off-limits to scrutiny on multiple occasions in 2012. The U.N. organization is concerned that the installation might have hosted development of a "neutron initiator" for activating atomic blasts and construction of "a large explosives containment vessel" suitable for nuclear-related testing.
Amano has said "extensive" reconstruction activities at the installation would "severely" compromise any future inspection. Pictures taken of the site from space in past months suggest Iran has torn down and built structures, transferred soil and placed temporary covering over sensitive areas, according to the Institute for Science and International Security in Washington.
In a telephone interview, former IAEA inspector Robert Kelley called for the agency to reduce its focus on Parchin and place higher priority on monitoring developments at Iran's Arak heavy-water reactor site. The Arak facility is slated to enter operation in the first quarter of 2014, the U.N. watchdog said in its November safeguards report.
"There are a lot of mysteries about that reactor like where the fuel is going to come from and how it's going to be made and what that reactor is really going to do since it looks exactly like a plutonium factory," Kelley said.
He questioned assertions that Iran might be concealing incriminating materials at Parchin. One side of the purported detonation chamber housing has been "largely untouched" by rebuilding activities, which "strongly suggests that the purpose of the earth-moving operations was for construction and renovation work and not for ‘sanitizing’ the site by covering up contamination," he wrote in a Friday analysis for the Stockholm International Peace Research Institute.
Iran's Foreign Ministry on Tuesday asserted the Parchin base had no role in the nation's atomic operations, but last week suggested Tehran could open the site to inspectors if the six world powers formally acknowledged its right to enrich uranium under the Nuclear Nonproliferation Treaty. Such a move could undercut a future multilateral bid to limit Iranian enrichment of uranium, Hibbs said.
The United States and partner governments say they worry Iran could eventually use its enrichment resources to produce weapon-grade uranium. Iranian leaders counter that the technology is intended only to fuel energy and other civilian pursuits.
In Washington, a former U.S. military official played down Iranian arguments that international scrutiny could endanger sensitive military information not relevant to nuclear concerns.
"They’ve been spending a long time cleaning up whatever was going on there," former Lt. Gen. Frank Kearney said during a panel discussion on Wednesday. "I find it rather hard to believe there’s any risk [to the Iranians] as they control the environment."