Major errors of concept and execution in the Iraq war have weakened the US: a sharp lesson in the limits of what seemed like limitless power. Its allies have been discredited, its enemies strengthened. Its real or wannabe rivals, China and Russia, are new global power centres. Its sway in Latin America and Africa has been compromised. The new Asian regional powers must steer a careful course in a complex world.By Charles Dumas, Diana Choyleva and Gabriel Stein.