The new Secretary-General of the United Nations, Antonio Guterres, defended on Tuesday the role of the United Nations as the "cornerstone" of the multilateral approach to solving the worst problems affecting the international community.Guterres, on his first day as head of the UN, delivered a brief message to United Nations employees in the main lobby of the organisation's headquarters, in which he repeated some of the principles he stood up for in his message last Sunday, EFE news reported.The Secretary-General said he feels proud to take the place of South Korean Ban Ki-moon for an initial term of five years, and also promised to do everything possible to rid the United Nations of its "straightjacket of bureaucracy".The Portuguese Guterres added that countries acting separately cannot possibly resolve the challenges currently facing the international community, which makes multilateral action positively essential."We need to recognise that only global solutions can address global problems and the UN is the cornerstone of that multilateral approach," he said.The UN Secretary-General promised to promote a dialogue with the organisation's personnel and insisted that only working as a team can the United Nations' goals be accomplished.