U.S. President Barack Obama is hopeful of Senate ratification this year of the arms reduction treaty with Russia he is signing in Prague on Thursday, a White House official said, according to Reuters. White House spokesman Robert Gibbs said "we hope and expect" ratification would be completed this year. Gibbs, who briefed reporters during Obama's flight to Prague, said there had traditionally been bi-partisan support for nuclear treaties. Obama and Russian President Dmitry Medvedev were due to sign the START II nuclear weapons reduction treaty in Prague later on Thursday. The treaty is a step toward an improvement in relations between Moscow and Washington strained since the war in Georgia in 2008. It is a boost for Obama's drive to reduce nuclear arsenals worldwide. Gibbs and White House deputy national security advisor Ben Rhodes said they expected Iran would be among issues discussed in Obama's meeting with Medvedev on Thursday. "The Russians are already committed to holding Iran accountable through the multilateral sanctions regime," Rhodes said. Rhodes noted the details of what the sanctions would look like were being hammered out in New York. He played down the prospect that specific agreements would be reached on Thursday. The White House said Obama also expected to discuss with Medvedev events in Kyrgyzstan, where the opposition said on Thursday it had taken power after deadly protests forced President Kurmanbek Bakiyev to flee the capital Bishkek.