President Obama: "Prime Minister Putin still has a lot of sway in Russia"
President Barack Obama has said Russia must understand that "old Cold War approaches" to relations with the US belong in the past.
The president said he would convey this to Vladimir Putin during talks in Moscow next week.
Mr Obama said the former Russian president - now prime minister - "still has sway" in Russia.
Earlier Russian President Dmitry Medvedev said he was hopeful of finding new ways to co-operate with the US.
In an interview with the Associated Press news agency, Mr Obama said Mr Putin was someone who has "one foot in the old ways of doing business and one foot in the new".
The president said the US was developing a "very good relationship" with Mr Medvedev, who succeeded Mr Putin last year.
The issue of reducing both countries' nuclear weapons will be high on the agenda during Mr Obama's visit, which begins on Monday.
The president said he was looking for progress on this, AP said.
Senior Russian and US officials held talks in May on a new treaty on cutting their stockpiles, paving the way for Mr Obama's trip.
The president told AP he did not regard Russia as an obstacle in dealing with North Korea and Iran. The US is trying to prevent both from possessing nuclear arms.
Mr Obama said there had been "good co-operation" from Russia in this regard, while warning that a nuclear-armed Iran might trigger an arms race in the Middle East.
Such a scenario would be a "recipe for potential disaster", he said.
Earlier, President Medvedev struck an upbeat tone on the forthcoming summit.
In a video on his website, he said the new US administration had demonstrated a willingness to build "effective, reliable and ultimately more modern relations".
"We are ready to play our part," he said.
He said the US and Russia were "united by the values of our civilisation, the values of respect for human life and human rights and freedoms".