The Obama administration was elated a month ago when the Russian president said sanctions against Iran for its nuclear program could become “inevitable.” Washington’s reaction may have been significantly .

Dmitry Medvedev’s words were seen as a major Kremlin shift and one that would buttress U.S. attempts to combine renewed negotiations with Tehran and a united front that threatened Iran with punishing global sanctions for failure to come clean about its nuclear ambitions.

The United States, Britain, France and Germany believe Iran is trying to build a nuclear weapon behind the cover of what Tehran says is a program designed solely to enable a homegrown network of reactors to generate electricity.

Russia and China, the other two key players who engage Iran on the nuclear issue, had routinely rejected tough sanctions, arguing that negotiations were the way forward.

But Medvedev emerged from talks with President Barack Obama on the sidelines of the U.N. General Assembly last month to declare of Iran: “In some cases, sanctions are inevitable.”

While clearly delighted with those words, the White House hotly rejected analyses that Medvedev was signaling a course change as a payoff for Obama’s decision a week earlier to scrap a missile defense shield in Eastern Europe. The U.S. missile system, conceived under the Bush administration purportedly to defend against attack from Iran, had become a major factor in deteriorating U.S.-Russian relations.

Nevertheless, the president’s top Russia adviser acknowledged that the decision against moving forward on missile defense — a deployment that Moscow said would have threatened its security — was a factor in Medvedev’s remarks.

“Is it the case that it (the missile defense decision) changes the climate — I think that’s true, of course,” Mike McFaul said at the time.

While Medvedev said sanctions could become necessary, Moscow was not long in telling Washington — and major trading partner Iran — that the time had not come yet. That clearly deflated expectations raised when Washington drew so much attention to Medvedev’s much hailed remarks.

“Threats, sanctions and threats of pressure in the current situation, we are convinced, would be counterproductive,” Russian Foreign Minister Sergey Lavrov said during U.S. Secretary of State Hillary Rodham Clinton’s visit to the Russian capital last week.

And Prime Minister Vladimir Putin, who absented himself on a trip to Beijing, drew a line under Lavrov’s comments.

“If we speak about some kind of sanctions now, before we take concrete steps, we will fail to create favorable conditions for negotiations,” Putin said. “That is why we consider such talk .”

Positions could clarify somewhat in talks Monday in Vienna, where the U.S., France, Russia, the U.N. nuclear agency and Iran hash out a proposal that would send some of Tehran’s low-grade enriched uranium to Russia for further processing to fuel an aging Iranian reactor used for medical research.

If expanded, that program might become the model for undercutting the need for Iran to continue with its own uranium enrichment, a technology which could shortly achieve the sophistication to create the weapons-grade material for use in a nuclear bomb.

And later this month, Iran will allow U.N. inspectors from the International Atomic Energy Agency to examine a newly disclosed uranium enrichment facility under construction near the holy city of Qom. Last month, Iran notified the IAEA of this facility just days before it was announced to the world by Obama, French President Nicolas Sarkozy and British Prime Minister Gordon Brown.

Iran’s new, if limited readiness to cooperate after years of stonewalling once its secret nuclear program became public could portend a more significant shift by Tehran. And Medvedev could be partly responsible.

“This time, it seems to me they (the Russians) are moving a bit to suggest to Tehran that Russia should not be taken for granted or ignored when it comes to meeting what Russia also says are legitimate expectations about Iranian behavior,” said James Collins, a former U.S. ambassador to Russia.