United Nations, Sept 25 (ANI): US President Barack Obama vowed at the United Nations to keep up the military pressure on Islamic State militants and urged those who have joined the extremist group in Iraq and Syria to "leave the battlefield while they can."Speaking at the UN General Assembly, Obama said Islamic State must be destroyed and issued a global call for nations to come together to join a US-led coalition. Before he spoke, US-led airstrikes for the third time this week pounded Islamic State targets in Syria and Iraq. He added that the United States does not intend to occupy any countries, but "will support Iraqis and Syrians fighting to reclaim their communities." He referred to Islamic State by the acronym ISIL.