While the familiar clashes among countries echo through the 193-member United Nations General Assembly hall this week, empty seats will bear mute testimony to the world body’s waning significance.

Some of the most important leaders — China’s Hu Jintao, Russia’s Vladimir Putin, Germany’s Angela Merkel and Turkey’s Recep Tayyip Erdogan — are skipping this year’s annual meeting. U.S. President Barack Obama made only a brief appearance and didn’t formally meet one-on-one with foreign officials.

The 67-year-old UN’s influence has always been limited by the veto power of the five permanent members of the Security Council. Now, however, global technological, financial, environmental, social, religious and demographic forces are further curbing its ability to act and eroding its foundation in the 17th century concept of sovereign nation-states.

‘The concept of a world of nation-states, which dates to the Treaty of Westphalia in 1648, and the idea that they have a monopoly on international relations and on the conduct of war, is no longer valid,