U.S. President Barack Obama and Russian leader Dmitry Medvedev are to announce a framework deal on arms cuts at a Kremlin summit on Monday intended to "reset" difficult relations between Moscow and Washington.
A U.S. official told Reuters that negotiators from both sides had agreed the text of an outline deal on cutting Russian and U.S. nuclear arsenals to put to the two presidents.
"There is text for them to review", the official said, speaking anonymously. The agreement would only become final once the two leaders had looked it over and announced it, he added.
During two days of talks, officials say Obama will win the Kremlin's consent to ship weapons to NATO forces in Afghanistan across Russian territory and create a joint government commission between Washington and Moscow to improve relations.
Business leaders travelling with Obama want to use the visit to boost trade and investment. Russian trade with the United States was just $36 billion in 2008, the same amount as with Poland, and investment has lagged that of European competitors.
"We hope that President Medvedev will be able to follow through on his continuous campaign to improve the rule of law," Andrew Somers, president of the American Chamber of Commerce in Russia, told Reuters in an interview.
"I think this is a single biggest inhibitor to investment by U.S. companies, their concern about the rule of law."
Obama will also listen to the country's embattled democratic opposition, meet former Soviet leader Mikhail Gorbachev and make a major speech to Russian students.
But he faces a harder task in trying to achieve his aim of a "reset" in relations between Washington and Moscow.
COLD GREY SKIES
The unseasonally cold, rainy, grey skies that awaited Obama and his family in Moscow seemed an appropriate metaphor for the state of relations between the two former Cold War superpowers.
Ties hit their worst level since the 1990s last year after Russia sent troops into neighbouring Georgia, a U.S. ally, triggering fierce condemnation from Washington.
Medvedev has said he is "moderately optimistic" about Obama's visit but the two sides are still deeply divided over U.S. plans to set up an anti-missile system in central Europe, something Russia says threatens its security.
This, as well as Russian resentment at NATO expansion into the former Soviet Union, could yet cast a shadow over the talks.
"Differences over fundamental issues are standing in the way of a complete 'resetting' of relations", the influential Kommersant daily said in a front page report.
"The parties have not yet come to an agreement on such fundamental issues as Russia's accession to the World Trade Organisation ... Georgia's territorial integrity and, most importantly, the USA's plans to deploy the elements of its missile defence system in Europe".
A poll released on the eve of Obama's arrival showed Russian distrust of the United States. The University of Maryland survey found 75 percent of Russians believed the United States abused its greater power and only two percent had "a lot of confidence" Obama would do the right thing in world affairs.
Medvedev, in an interview released on Sunday, said the United States would only get a full arms control treaty with Moscow if it dropped unilateral plans for missile defence -- a linkage which Obama has rejected.
The U.S. leader also faces an awkward first meeting on Tuesday with Prime Minister Vladimir Putin, Russia's most powerful politician, after publicly criticising him last week.
Obama, in an interview, said Putin still had one foot mired in Cold War thinking and compared him unfavourably with Medvedev, Putin's chosen successor as president. Putin hit back, saying Russians "are standing firmly on both feet".
In an indication of the strained atmosphere, Russia's Kremlin-controlled main television channels -- the chief source of news for most Russians -- have played down Obama's visit.
"This is being played as essentially a low-key visit that shows the American leadership's respect for the Russian leadership," Dmitry Trenin, head of the Moscow Carnegie Centre think-tank, said. "This is not some star coming to town."
The Other Russia and Solidarity opposition movements announced plans for a protest rally in central Moscow on Monday evening to coincide with Obama's visit.