Leon Panetta with Ng Eng Hen, Singapore's defense minister.At the start of his long journey across Asia, Secretary of Defense Leon Panetta told the Shangri-La Security Dialogue that the United States would play a greater role in the security of the Asia-Pacific region.

Specifically, Panetta explained, the United States would focus on “promoting strong partnerships that strengthen the capabilities of the Pacific nations to defend and secure themselves.” (Emphasis mine)

In a speech with the requisite amount of hand-waving and pleasing rhetoric, this statement stands out as one that is eminently measurable. If the U.S. strategy in the Asia-Pacific region succeeds, ten or fifteen years from now we will have observed that countries in the region expanded their military capabilities, such that they are better able to secure their territory and their wider interests. That was Panetta’s goal, clearly set forth in the speech, and he is speaking for the entire Obama administration.

How this will play out is still quite murky. If the pivot works as planned, does that mean that the Asian allies will be spending more money on their militaries? Not necessarily. Will they be better able to operate independent of the United States? Not clear. Panetta’s speech declared that the United States would “modernize and strengthen” existing “partnerships in the region.” Does that imply that there will be fewer troops in Europe and more in Asia? Probably not. Panetta has stressed, and he did again in Singapore, that there will be a U.S. presence in Asia, but it would be more flexible. The Asia-Pacific and Indian Ocean regions are obviously more conducive to air and naval operations, and there is little need (and therefore little enthusiasm) for a vastly larger U.S. ground presence.

But while we can’t know the precise disposition of U.S. forces in the region in the future, we can assess where they are now, and where they have been. A recent issue of Defense News (June 4, 2012) includes a map of the region showing where U.S. troops are located and in what numbers. The data is compiled from this quarterly report plus a separate report on deployments in South Korea (numbers which are curiously excluded from the 309A report).

All told, the numbers are quite small. Of the nineteen countries listed, thirteen hosted fewer than one hundred U.S. military personnel. There were more Americans stationed in China (seventy-four) than in India, Indonesia and Bangladesh combined (seventy-one). And a substantial share of the U.S. military presence in the Asia-Pacific is based in Hawaii (42,502) and Guam (4,272).

Panetta reminded his audience that the U.S. military presence in Japan (36,708) and South Korea (18,470) will be smaller in the future, but this too is a continuation of a very long-term trend. Consider, for example, that there were 136,554 U.S. active-duty personnel in Japan (including Okinawa and the Ryukyu Islands) in 1950, 82,264 in 1970 and just 46,593 in 1990. (The historical data can be found here.) The presence has leveled off since then but is likely to decline still further as more U.S. personnel are moved to Guam. This move, Panetta explained in Singapore, “will make the U.S. presence in Okinawa more politically sustainable, and it will help further develop Guam as a strategic hub for the United States military in the Western Pacific”

To recap: the U.S. military presence in the Asia-Pacific region has been steadily declining for decades, particularly the number of active-duty personnel stationed in East Asia. Panetta implies that this trend will continue, but he also stressed that “the United States will play a larger role in [the] region.” The U.S. Navy is expected to boost its presence, but it is unclear exactly where or how. Singapore agreed “in principle” to host four littoral combat ships on “a rotational basis,” but that doesn’t come close to meeting Panetta’s promise to deploy 60 percent of U.S. Navy assets to the Asia-Pacific by 2020 (the current split between the Atlantic and Pacific is 50-50).

Another big unknown: Will the countries in the region be as committed to their own security as Panetta imagines? One way to measure this (though not the only way) is by the amount of money that each country is willing to dedicate to its military. The trends are not promising. IISS’s The Military Balance 2012 notes dryly that “elevated growth rates across Asia have not necessarily translated into equivalent increases in defence spending.” Over the past ten years, 2001–2010, spending as a share of GDP has fallen from 2.83 to 1.94 percent in the South and Central Asia Region, and it has not budged in East Asia and Australasia (1.41 percent in 2001; 1.44 percent in 2010).

This is not surprising, especially given that U.S. spending rose dramatically during this same period, from 3.0 percent in 2001 to 4.8 percent of GDP in 2010. Much of this growth was driven by the wars in Iraq and Afghanistan and therefore not directed toward the Asia-Pacific region, per se. Still, people are disinclined to pay for things that others will provide them for free, and U.S. grand strategy, and the military posture that flows from it, discourages other countries from spending more on their defense.

American policy makers frequently complain about our allies doing too little or not sharing the burden more equitably, but many are content with the status quo. Fearful that other countries might either a) grow too capable militarily, appear threatening to their neighbors and precipitate regional arms competition, or b) allow security challenges to fester and grow, necessitating U.S. involvement at a later date, Washington has preferred to maintain a forward military presence in both Europe and Asia in the hopes of preventing either from happening. We cannot know what would have occurred if Washington had withdrawn U.S. military personnel from both regions after the collapse of the Soviet Union, but we can see that U.S. taxpayers have incurred higher costs, and U.S. troops have borne greater risks, while other countries have done relatively less. At times, U.S. policy makers seem to be quite worried that other countries might acquire greater military capability and be more inclined to use it, but that has not occurred; most of America’s allies were militarily weak at the end of the Cold War, and they have allowed their hard power capability to atrophy further since then.

In ten or fifteen years, will we declare the pivot to Asia a success if we see this trend reversed, if Americans are spending less as a share of regional military expenditures, and if the countries in the region are contributing more? I would. I think that a majority of Americans would. But I remain skeptical that the foreign-policy establishment here in Washington feels the same way.