When I write about our new G-Zero world, I am describing an international phenomenon: a global environment in which no power or group of powers can sustainably set an international agenda. The global community, used to orienting itself around a collection of U.S.-led powers, has fallen victim to a widening leadership vacuum, what with the United States disengaging from foreign affairs and Europe too busy with its own crisis. Emerging powers like China have grown large enough to undermine a Western-led global agenda — but not yet developed enough to prioritize their own international role over their domestic concerns.