Russia's President Dmitry Medvedev (second left) and United States President Barack Obama have burgers for lunch at Ray's Hell Burger restaurant in Arlington in Virginia on Thursday.

At a joint press conference with his Russian counterpart on Friday, Obama said he has 'reset' the button of relationship with America's Cold War adversary Russia.

"We have made significant progress and achieved concrete results," he said.

Photograph: Kevin Lamarque/Reuters