Top Obama aide heads to Moscow

President Barack Obama\'s national security adviser Tom Donilon travels to Moscow Thursday, as \"reset\" U.S.-Russia relations brace for a test posed by the return to the presidency of Vladimir Putin. Donilon will be in Moscow for two days, National Security Council spokesman Tommy Vietor said, ahead of the presidential inauguration on May 7. He will meet \"senior officials in order to review key issues in our bilateral and international agenda as well as to consult on upcoming US-Russian high-level engagement,\" Vietor said. Obama and Putin are expected to meet on the sidelines of the G8 summit that the US leader will host at his presidential retreat at Camp David, Maryland on May 18-19. The US leader enjoyed a close relationship with outgoing Russian President Dmitry Medvedev, who is expected to become Putin\'s prime minister, but uncertainty clouds US-Russia relations with the ex-KGB man\'s return to the pinnacle of power at the Kremlin. Obama called to congratulate Putin in March after he won the Russian election, despite earlier US concern over reported vote irregularities. The two leaders \"agreed that the successful reset in relations should be built upon during the coming years\" the White House said. The two sides have been at odds over US plans for missile defense in Europe and the uprising in Syria, which has had a close relationship with Moscow. Putin\'s return to power has also raised questions over whether the former KGB man\'s abrasive approach and strident criticism of the United States, will begin to exert a toll on US-Russia relations.