U.S. President Barack Obama said on Monday the international community should have done more to avoid a leadership vacuum in Libya, which has been in disarray since the fall of Muammar Qaddafi four years ago. Obama told the United Nations General Assembly the international community must work harder in future to ensure states do not implode. The rapid descent of Libya into violent chaos was one of the most dramatic events in the "Arab Spring," the abrupt collapse of long-standing autocratic governments in a number of Arab countries in the face of popular protests.