US Secretary of State Hillary Clinton has told the BBC that Russia now recognises the threat posed by Iran.
Wrapping up a European tour in Moscow, Mrs Clinton said Russian leaders had in private said they were ready to act if Tehran did not meet its obligations.
Russian Foreign Minister Sergei Lavrov said on Tuesday that sanction threats against Iran were counter-productive.
Iran denies Western allegations it is trying to build the bomb under cover of a civilian nuclear energy programme.
Mrs Clinton told the BBC on Wednesday that Russia in the past six months had "moved tremendously" to acknowledge the threat of Iran's programme.
She said Russian officials, in private talks, had recognised the need to act if diplomacy failed.
"We are in total agreement on all of that," Mrs Clinton told the BBC.
"And we are also in agreement that if our diplomatic engagement is not successful then we have to look at other measures to take, including sanctions to try to pressure the Iranians."
As a permanent UN Security Council member, Russia would need to back any fresh sanctions against Iran.
Iran agreed at a meeting in Geneva at the start of this month to allow UN inspectors into a previously undisclosed nuclear site near its holy city of Qom, and to send low-enriched uranium abroad for enrichment to a higher level.
Mrs Clinton acknowledged to the BBC that Tehran had bought itself more time with this move.
But she said Tehran had also made commitments which the Russians and the Chinese now expected them to fulfil.
Putin absent
The US secretary of state could not meet Russia's key decision-maker, Prime Minister Vladimir Putin, as he was visiting China.
Later, she headed for Kazan, the capital of the religiously and ethnically diverse region of Tatarstan, east of Moscow.
Her five-day European trip has included stops in Zurich, London and Belfast.
Earlier, Mrs Clinton urged Russia to respect human rights and democracy.
She was pressed by reporters on the failure of the Russian authorities to find the killer of journalist Anna Politkovskaya, and on the imprisonment of ex-tycoon Mikhail Khodorkovsky.
"I think we want the government to stand up and say this is wrong," she told Moscow radio station Echo.
US President Barack Obama, who met Mr Medvedev in July, has pledged to reset relations with Russia.
A month ago, following the revelations about Iran's second uranium enrichment facility at Qom, the Russian president said his government might ultimately accept further sanctions as inevitable.
Mr Obama, for his part, has met a key Russian demand to scrap plans to deploy interceptor missiles in Poland and a radar station in the Czech Republic as part of a US missile defence system in Europe.
The US administration insisted it did not expect concessions in return.
But US officials have called on Russia to support, or at least not oppose, the idea of the UN Security Council imposing tougher sanctions on Iran if it fails to live up to its international obligations.
The council wants Iran to end uranium enrichment and has approved three rounds of sanctions - including bans on Iran's arms exports and all trade in nuclear material.
SOURCE : BBC
Wrapping up a European tour in Moscow, Mrs Clinton said Russian leaders had in private said they were ready to act if Tehran did not meet its obligations.
Russian Foreign Minister Sergei Lavrov said on Tuesday that sanction threats against Iran were counter-productive.
Iran denies Western allegations it is trying to build the bomb under cover of a civilian nuclear energy programme.
Mrs Clinton told the BBC on Wednesday that Russia in the past six months had "moved tremendously" to acknowledge the threat of Iran's programme.
She said Russian officials, in private talks, had recognised the need to act if diplomacy failed.
"We are in total agreement on all of that," Mrs Clinton told the BBC.
"And we are also in agreement that if our diplomatic engagement is not successful then we have to look at other measures to take, including sanctions to try to pressure the Iranians."
As a permanent UN Security Council member, Russia would need to back any fresh sanctions against Iran.
Iran agreed at a meeting in Geneva at the start of this month to allow UN inspectors into a previously undisclosed nuclear site near its holy city of Qom, and to send low-enriched uranium abroad for enrichment to a higher level.
Mrs Clinton acknowledged to the BBC that Tehran had bought itself more time with this move.
But she said Tehran had also made commitments which the Russians and the Chinese now expected them to fulfil.
Putin absent
The US secretary of state could not meet Russia's key decision-maker, Prime Minister Vladimir Putin, as he was visiting China.
Later, she headed for Kazan, the capital of the religiously and ethnically diverse region of Tatarstan, east of Moscow.
Her five-day European trip has included stops in Zurich, London and Belfast.
Earlier, Mrs Clinton urged Russia to respect human rights and democracy.
She was pressed by reporters on the failure of the Russian authorities to find the killer of journalist Anna Politkovskaya, and on the imprisonment of ex-tycoon Mikhail Khodorkovsky.
"I think we want the government to stand up and say this is wrong," she told Moscow radio station Echo.
US President Barack Obama, who met Mr Medvedev in July, has pledged to reset relations with Russia.
A month ago, following the revelations about Iran's second uranium enrichment facility at Qom, the Russian president said his government might ultimately accept further sanctions as inevitable.
Mr Obama, for his part, has met a key Russian demand to scrap plans to deploy interceptor missiles in Poland and a radar station in the Czech Republic as part of a US missile defence system in Europe.
The US administration insisted it did not expect concessions in return.
But US officials have called on Russia to support, or at least not oppose, the idea of the UN Security Council imposing tougher sanctions on Iran if it fails to live up to its international obligations.
The council wants Iran to end uranium enrichment and has approved three rounds of sanctions - including bans on Iran's arms exports and all trade in nuclear material.
SOURCE : BBC