Invoking his heroes Mahatma Gandhi and legendary civil rights leader Martin Luther King, US President Barack Obama today received the 2009 Nobel Peace Prize vowing to achieve a peaceful world where war is sometimes necessary.<br/><br/>In his acceptance speech after receiving the Nobel Prize, the first sitting US President to get the coveted prize in 90 years, Obama said there is nothing weak-nothing passive – nothing na’ve – in the creed and lives of Gandhi and King.<br/><br/>Mr. Obama said but as a head of state sworn to protect and defend my nation, he cannot be guided by their (Gandhi and Dr King) examples alone.<br/><br/>The president acknowledged that many people feel he has not done enough to deserve the prize that he received in Oslo. He also noted that he recently ordered another 30,000 U.S. troops to fight in Afghanistan.<br/><br/>People must accept the hard truth that violence cannot be eradicated and nations sometimes must wage war to protect their citizens from evil regime or terrorist groups.<br/><br/>Describing disarmament as a centerpiece of his foreign policy, Obama said he was committed to upholding the nuclear non-proliferation treaty and that he was working with Russian President Medvedev to reduce America and Russia's nuclear stockpiles.