The U.S. ambassador to the United Nations on September 28 said Russia is trying to "shield Iran" from inspections by the UN's nuclear watchdog of some activities that could contribute to developing a nuclear bomb.
Nikki Haley has been pushing to increase and broaden the inspections conducted by the UN's International Atomic Energy Agency (IAEA), which is charged with monitoring compliance with restrictions on nuclear activities that Tehran agreed to in exchange for sanctions relief under the 2015 nuclear deal.
But while Haley has been urging the watchdog to broaden its inspections in Iran, UN diplomats say Russia has been trying to diminish the agency's role by arguing it has no authority to police one critical section of the deal.
That section, known as section T, bans "activities which could contribute to the development of a nuclear explosive device." It lists examples such as using computer models that simulate a nuclear bomb, or designing multi-point, explosive detonation systems.
Unlike many other parts of the deal, section T makes no mention of the IAEA and does not specify how compliance with the section will be verified.
UN diplomats said Russia is arguing that means the IAEA has no authority to monitor compliance with the section by conducting inspections. Russia is one of the six world powers that signed the deal with Iran.
The United States and its Western allies Britain, France, and Germany, which also signed the deal, disagree with Russia's interpretation, and Haley took their case public in a statement at the UN.
"If the Iran nuclear deal is to have any meaning, the parties must have a common understanding of its terms," Haley said.
"Iranian officials have already said they will refuse to allow inspections at military sites, even though the IAEA says there must be no distinction between military and non-military sites.
"Now it appears that some countries are attempting to shield Iran from even more inspections," Haley said. "Without inspections, the Iran deal is an empty promise."
The matter is particularly important to the United States right now because U.S. President Donald Trump faces a mid-October deadline for deciding whether to certify that Iran is in compliance with the deal.
Haley has said his certification is in doubt unless the IAEA is able to conduct broader and more vigorous inspections of Iran's sites and activities.
Iran and Russia have not commented publicly on the matter.
Earlier this month, the head of the Iranian nuclear program, Ali Akbar Salehi, accused Washington of trying to sabotage the agreement by demanding more inspections, and called on the IAEA to resist Washington's "unacceptable demands."
With reporting by AFP and Reuters