… secondo Robert Kaplan (Stratfor):

The Obama administration “pivot” to the Pacific, formally announced by Secretary of State Hillary Clinton last November and reiterated more recently by the president himself, might appear like a reassertion of America’s imperial tendencies just at the time when Washington should be concentrating on the domestic economy. But in fact, the pivot was almost inevitable.
When the Berlin Wall fell in 1989, signaling communism’s defeat in Europe, security experts talked about a shift in diplomatic and military energies to the Pacific. But Saddam Hussein’s invasion of Kuwait in 1990 led to a decadelong preoccupation with the Middle East, with the U.S. Army leading a land war against Iraq in 1991 and the Navy and Air Force operating no-fly zones for years thereafter. Then came 9/11, and the Bush administration’s initiation of wars in Afghanistan and Iraq as a response. Finally, the ending of both those conflicts is in sight, and the United States, rather than return to quasi-isolationism as it has done with deleterious effect after other ground wars in its history, is attempting to pivot its focus to the geographical heart of the global economy: the Indian and Pacific oceans.
The Indian Ocean is the world’s energy interstate, across which passes crude oil and natural gas from the Arabian Peninsula and Iranian Plateau to the burgeoning, middle-class urban sprawls of East Asia. Though we live in a jet and information age, 90 percent of all commercial goods that travel from one continent to another do so by container ship, and half of those goods in terms of global tonnage — and one-third in terms of monetary value — traverse the South China Sea, which connects the Indian Ocean with the Western Pacific. Moreover, the supposedly energy-rich South China Sea is the economic hub of world commerce, where international sea routes coalesce. And it is the U.S. Navy and Air Force, more than any other institutions, that have kept those sea lines of communication secure, thus allowing for post-Cold War globalization in the first place. This is the real public good that the United States provides the world. But now a new challenge looms for the United States: a rising China as demonstrated by the totality of its power — its geographical proximity to the South China Sea and environs; its economic heft, making it the largest trading partner of most if not all of the littoral nations (despite economic troubles in China itself); and its expanding submarine fleet. Beijing has been buying smart, investing in subs, ballistic missiles, and space and cyber warfare as part of a general defense build-up. China has no intention of going to war with the United States, but it does seek to impede in time of crisis U.S. military access to the South China Sea and the rest of maritime Asia. […]
Were the United States not now to turn to the Indo-Pacific, it would risk a multipolar military order arising up alongside an already existent multipolar economic and political order. Multipolar military systems are more unstable than unipolar and bipolar ones because there are more points of interactions and thus more opportunities for miscalculations, as each country seeks to readjust the balance of power in its own favor. U.S. military power in the Indo-Pacific is needed not only to manage the peaceful rise of China but also to stabilize a region witnessing the growth of indigenous civil-military post-industrial complexes.
If American power was diminished, China, India and other powers would be far more aggressive toward each other than they are now, for they all benefit from the secure sea lines of communication provided by the U. S. Navy and Air Force.