Deputy Israeli Prime Minister Avigdor Lieberman told the German weekly Der Spiegel in an interview published Saturday that the formation of a Palestinian unity government should not result in Hamas being given a "blank check." "I am worried that a Palestinian government of national unity will give Hamas the international legitimacy that it so far has lacked - without it recognizing Israel or ending the tactics of terror against us," he was quoted as saying. Lieberman, who serves as the minister for strategic threats, also expressed concern at developments over Iran's disputed nuclear program. "The differences of opinion between Russia and western Europe, between Europe and the USA, between the USA and the UN, have destabilized the world political system," he said, Der Spiegel reported. "We must reckon with the international community doing nothing and with Israel having to act alone at some point."