Russian President Dmitry Medvedev and Czech President Vaclav Klaus arrive at Prague Castle in Prague, April 8, 2010. President Medvedev and U.S. President Barack Obama will sign a new Strategic Arms Reduction Treaty (START II) later today, that could herald better bilateral ties and help Obama raise pressure on countries seeking to develop nuclear weapons. REUTERS/Petr Josek (CZECH REPUBLIC - Tags: POLITICS)