UNITED NATIONS - Ban Ki-moon, who was unanimously approved by the UN General Assembly on Tuesday for a second five-year term as the secretray-general, said he would work as a "harmonizer and bridge-builder among member states," to advance the cause of world peace in these turbulent times. Ban, who is seen as a solid U.S. ally, told the 192-member Assembly that he was proud and humbled to accept the appointment. As Secretary-General, I will work as a harmonizer and bridge-builder among Member States, within the United Nations system, and between the United Nations and a rich diversity of international partners, Ban said. He stressed that no challenge is too large. Together, nothing is impossible, he said, noting that the worlds peoples are looking more and more to the UN to lead on key issues. We knew then and more so now that we live in an era of integration and inter-connection, a new era when no country can solve all challenges on its own and where every country should be part of the solution. That is the reality of the modern world. We can struggle with it, or we can lead. Ban said the UN had laid a firm foundation for the future on a number of issues since he assumed office, including climate change, nuclear disarmament, education, sustainable development and global health. We are on track to eliminate deaths from malaria. With a final push, we can eradicate polio, just as we did smallpox long ago. We have shielded the poor and vulnerable against the greatest economic upheaval in generations. The Secretary-General also cited the UNs peacekeeping efforts in conflicts and crises around the world, the creation of the agency known as UN Women, and the UNs response to major humanitarian disasters in Haiti, Pakistan and Myanmar. Looking ahead, he noted that the current economic times in the wake of the global financial crisis meant the world, and the UN as an institution, have to do more with less. We must do more to connect the dots among the worlds challenges, so that solutions to one global problem become solutions for all on womens and childrens health, green growth, more equitable social and economic development. A clear time frame lies ahead: the target date for the Millennium Development Goals (MDGs) in 2015, next years Rio+20 conference, the high-level meeting on nuclear safety in September and the nuclear security summit in Seoul next year.he former South Korean foreign minister, who took over as U.N. secretary-general from his predecessor Kofi Annan in 2007, was re-elected to the world body's top job by acclamation, effective next January 1. Ban, 67, was unopposed, making his re-election a virtual certainty after the Security Council last week recommended he continue at the helm of the United Nations. He thanked the U.N. member states for the "great honor" they bestowed on him but later told reporters he had much unfinished business. "Clearly we have far to go," Ban said. "Too many people lack basic human rights. Too many people are hungry. Too many children die needlessly every day." "Seldom has the United Nations been more relevant and never has it been more necessary," he added. U.S. Ambassador to the United Nations Susan Rice welcomed Ban's re-election and praised his performance in "one of the toughest jobs in the world." "No one understands the burdens of this role better than he," Rice said, adding that Washington was "grateful that he is willing to take them on." Under an unwritten U.N. rule, the job of secretary-general rotates among the world's regions and may not be held by a citizen of one of the five permanent Security Council members -- the United States, Britain, France, Russia and China.