US President Barack Obama has revived a civilian nuclear energy pact with Moscow, which was shelved in the wake of Russia’s 2008 conflict with Georgia.
Mr Obama resubmitted the pact to Congress, saying US-Russian co-operation over Iran justified the move.
The planned agreement would allow the transfer of technology and equipment, including reactors.
Mr Obama has vowed to "reset" relations with Moscow, which became strained under his predecessor George W Bush.
As well as co-operating on Iran, Russia and the US have also this year agreed to replace the Strategic Arms Reduction Treaty governing nuclear arsenals.
Washington summit
In his letter to Congress, Mr Obama said: "The level and scope of US-Russia co-operation on Iran are sufficient to justify resubmitting the proposed agreement to the Congress.
"I have determined that performance of the proposed agreement will promote, and will not constitute an unreasonable risk to, the common defence and security."
The pact had been signed in 2007 by Mr Bush and Vladimir Putin, who was Russian president at the time.
But the conflict in Georgia meant the deal was never put to a Senate vote.
Russia and the US have taken a number of steps on nuclear issues this year.
Last month they agreed a new Strategic Arms Reduction Treaty, reducing each country’s deployed nuclear arsenal to 1,550 weapons.
Also last month the nations agreed to dispose of tonnes of surplus weapons-grade plutonium under a deal signed at a nuclear summit in Washington.
The war between Georgia and Russia was sparked by fighting in Georgia’s breakaway region of South Ossetia in August 2008.
Hundreds of people are thought to have died in the five-day-long conflict and thousands were displaced.
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