Russia has paid tribute to its citizens who lost their lives helping defeat Nazi Germany in World War II.About 50 world leaders have joined the Russian President, Vladimir Putin, in Red Square in Moscow for a Victory Day parade.Other VIPs included the Presidents of China, France and the US, the German Chancellor, as well as the Prime Ministers of Japan, Turkey, Italy and India.There was tight security in Moscow, amid fears that Chechen rebels might try to launch terrorist attacks.In his speech to those gathered, President Putin paid tribute to the 26.6 million Soviet citizens who lost their lives during the war.He thanked the US, British and French allies, saying that people should never be allowed to forget what happened during the conflict. He also highlighted the importance of reconciliation, pointing towards the good relations now between Russia and Germany. There has been controversy, however. Estonia and Lithuania stayed away from the events. They say the defeat of Nazi Germany meant the start of a second tyranny under Soviet communist rule.Georgia has also stayed away, in protest at failure to reach a deal on the closure of two Soviet-era military bases on Georgian soil. After the parade, in which more than seven thousand military personnel and veterans took part, the world leaders attended a wreath-laying ceremony at the tomb of the unknown soldier near the Kremlin.