US President George W. Bush and Russian President Vladimir Putin failed to overcome sharp differences over a US missile defense system, closing their seven-year relationship Sunday still far apart on an issue that has separated them from the beginning. "Our fundamental attitude toward the American plan has not changed," Putin said at a news conference with Bush at his vacation house at this Black Sea resort. "We got a lot of way to go," Bush said. Despite the impasse, the two leaders agreed that Moscow and Washington would work together closely in the future on missile defense and other difficult issues. Bush also conferred with Putin's hand-picked successor, Dmitry Medvedev, but did not claim gaining any insight into his soul, as he had with Putin upon their first encounter. He pronounced Putin's protege "a straightforward fellow" and said he was eager to work with him. Putin was asked whether he - or Medvedev, the president-elect - would be in charge of Russia's foreign policy after May 7, when Putin steps down as president and is expected to be named prime minister.