The most important geo-political change of the last few years is not the resurgence of Russian aggression, nor the Arab spring; it is the American pivot to East Asia. The U.S. is shifting its focus from the Middle East to contain China, strengthening regional alliances to curb Chinese attempts to expand their sphere of influence.
While much ink has been spilled over the strategy, few seem to actually understand the basic tradeoff. America can limit Chinese sphere of influence by (slightly) raising the possibility of war. We can imagine a circle around China; the larger the circle, the lower the probability of war. However, the countries inside the circle are less likely to have democracy and open markets.
Policy preferences are going to depend on the relative weights placed on the alternatives. If you believe the probability of war is slight, or you discount the cost of war, you will prefer a more aggressive containment strategy. On the other hand, if you think China will allow relatively open markets, or think the cost of war is high, you will allow China to peacefully expand.
People on both sides of the debate will deny these terms. Neocons will argue the probability of war is so close to zero it can be ignored. Noninterventionists will ignore the unfree markets that China imposes on its neighbors. However, as it is probable this tension will continue for at least a decade, it is worth understanding the tradeoffs being faced.