NEW YORK — The world's economies are becoming more interdependent than ever, but economic nationalism, protectionism and beggar-thy-neighbor attitudes are threatening the bonds of trust and cooperation that a truly globalized economy requires.

To prevent another recession or worse, the leaders of the 20 wealthiest nations must take aggressive action at the semi-annual Group of 20 summit in Seoul to develop a broad agenda for more balanced, equitable and sustainable global growth — and to oversee its strict implementation.

Five principles should guide their thinking: