Don't look to Washington.
The United States will remain the world's most powerful nation for years to come, but the Obama administration and U.S. lawmakers are now focused on debt, immigration, guns and growth.
A war-weary, under-employed American public wants results at home, leaving U.S. officials to look for allies willing to share costs and risks abroad.
Unfortunately, it's not easy to build and sustain alliances in a world where America can't afford its traditional share of the heavy lifting.
No wonder then that the Obama administration's greatest foreign policy successes haven't depended on such alliances.
Withdrawing troops from Iraq and Afghanistan doesn't require consensus among the world's powers. President Barack Obama's single indisputable foreign policy triumph, the killing of Osama bin Laden, needed buy-in only from the members of Seal Team 6.
Nor should we look to Europe for help. Its leaders are still hard at work duct-taping the euro zone, and cash-strapped governments consider an activist European foreign policy prohibitively expensive.
Nor will next-wave powers look to shoulder new burdens. Economic slowdowns in China, India and Brazil remind us that not every emerging market will fully emerge, much less accept the costs and risks that come with a share of global leadership.
In this G-Zero world, where no single government or alliance can lead others toward compromise, solutions to transnational problems range from ad hoc to beyond reach. United Nationsl Secretary General Ban Ki-moon opened the U.N.'s Conference on Sustainable Development last June with a warning: This gathering is too big to fail.
But for Obama, German Chancellor Angela Merkel and British Prime Minister David Cameron, the event was simply too big to attend. None of them has the muscle, individually or together, to force compromise on the policies that fuel climate change - and they know it.
This leadership vacuum continues to expand. The risk of confrontation in Asia has grown - between China and Japan (the world's second- and third-largest economies) in the East China Sea, and between China and several Southeast Asian countries in the South China Sea.
Making matters even more dangerous, the U.S. transition toward a sharper foreign policy focus on Asia, progress toward a massive U.S.-led transpacific trade deal that excludes China and conflict in the under-governed expanse of cyberspace are worsening tensions between Washington and Beijing.
Fights over commercial and investment rules and the clash between the state-driven and free-market varieties of capitalism have gathered momentum. In years to come, no ties will be more important for global peace and prosperity than those that bind America and China, the world's most powerful developed and developing states, and no development would more quickly exacerbate the G-Zero dilemma than a dramatic worsening of relations between them.
In the Middle East, Syria's civil war grinds on with worrisome implications for Turkey, Iran, Saudi Arabia and even Russia. Sectarian tensions are again stoking violence in Iraq. Attacks on U.S. diplomatic targets in Libya, Egypt and Yemen have heightened Washington's aversion to direct involvement in the region's conflicts. This is another region in which a lack of global leadership and rivalries among local heavyweights ensure that pain will get worse before real progress can be made.
Ironically, the nation most likely to fill the leadership vacuum left by America the Vulnerable is America the Resilient. A technology-driven U.S. energy boom has begun to create jobs, revitalize U.S. manufacturing and offer Washington the chance to use exports of natural gas, technology and knowhow to reverse the decline in U.S. international influence.
Over the longer term, Washington will have to address the growing imbalances on U.S. books, but as the financial crisis reminded us, when volatility and fear are the order of the day, safety becomes the world's most valuable commodity. That's why the United States remains the world's investment safe haven - and why, for better and worse, not even ratings agency downgrades can make it more difficult for America's government to borrow money, at least for the moment.
Nor is it inevitable that America and China will collide. Washington and Beijing seem at times destined for conflict, a dispute more likely to be fought in financial markets and in cyberspace than on more familiar battlegrounds. Yet heavy volumes of bilateral trade and investment ensure that neither side has much to gain from the other's weakness.
The two countries can't afford a zero-sum, Cold War-style confrontation, and both governments know it. It remains to be seen, however, if Presidents Obama and Xi Jinping have the vision and political will to build the sort of pragmatic partnership that might finally bring the G-Zero era to an end.© (c) Copyright Thomson Reuters 2013.