MOSCOW — Secretary of State Hillary Rodham Clinton had barely arrived in Moscow for nuclear arms and Mideast talks when tensions over Iran flared up publicly Thursday.
Meeting with reporters alongside her Russian counterpart, Foreign Minister Sergey Lavrov, Clinton reproached Moscow for building and fueling a nuclear power plant in Iran. Tehran is not entitled to generate nuclear energy for civilian purposes, Clinton said pointedly, until it puts to rest suspicions that it is secretly pursuing a nuclear weapons program.
Earlier Thursday, Prime Minister Vladimir Putin announced that the Russian-built reactor will begin to generate electricity in Iran as soon as this summer.
"If (Iran) reassures the world, or if its behavior is changed because of international sanctions, then they can pursue peaceful, civil nuclear power," Clinton said. "In the absence of these reassurances, we think it would be premature to go forward with any project at this time because we want to send an unequivocal message" to Iran.
At her side, Lavrov held his ground.
"Russia is involved, and this project will be completed," Lavrov said. "This nuclear power plant will finally be launched, and it will generate electricity."
Lavrov argued that the plant is crucial to the International Atomic Energy Agency's presence in Iran, providing a foothold to monitor whether Tehran complies with nonproliferation requirements.
The clash underlined lingering and sticky disagreements between the United States and Russia over how best to confront Iran. The Obama administration badly needs Russian backing in order to pursue more aggressive action against Iran and has been pressing Moscow for support.
There was some speculation that those efforts were beginning to bear fruit in recent months, as Russian officials periodically sounded bursts of harder rhetoric against Iran's nuclear program.
But Russia, which maintains close business and diplomatic ties with Iran, has adroitly sidestepped pressure to publicly commit to tougher sanctions.
Russia and China, which also has resisted taking a tougher approach with Iran, are permanent members of the U.N. Security Council and can thus veto any U.S.-backed resolution imposing extra sanctions on Iran.
In 2007, Russia said Iran had lagged on its payments and that the plant opening might be delayed. Rumors swirled that U.S. pressure had finally convinced Moscow to drag its feet.
But the project has since regained its momentum.