Ever since World War II, the United States has sought the capacity to wage two major military operations at once.
In the aftermath of the Cold War, the Bush and Clinton administrations have focused on simultaneous conflicts against Iraq and North Korea, with both wars assumed to resemble Desert Storm in scale and character.
Defense Secretary Donald Rumsfeld has now made it plain that he wants to rethink this approach to sizing U.S. combat forces. Yet recent reports suggest that he is still groping for a new framework.
Some type of two-war capability surely still does make sense for the United States. If it lacked such a capability, and had to go to war in one place, an opportunistic aggressor might be tempted to strike elsewhere.
Those skeptical that the United States needs a two-war capability should consult recent history.
For example, in 1994 Iraq moved armored forces toward Kuwait just weeks after the United States and its allies nearly fought North Korea over the latter's nuclear reactors.
In 1996, we had to face both a missile crisis in the Taiwan Strait and another one of Saddam Hussein's provocations, this one an attack against Kurdish groups in northern Iraq. In neither of these instances did simultaneous major wars occur. But they could have, especially if potential adversaries had doubted our abilities.
But even if one accepts the two-war logic, big questions remain. Whom might we need to fightand over what stakes? Today's Pentagon focuses on preparing to refight Iraq and North Korea. It further envisions using a very specific force packagesix to seven ground combat divisions, 10 fighter wings, four to five aircraft carriers, and in all about half a million GIsagainst each opponent.
In both cases, it is assumed that the United States would first see its regional allies largely overrun, and then need to mobilize a huge force to stabilize the situation, reverse the aggression and possibly overthrow the offending aggressor government while occupying its country.
As Mr. Rumsfeld rightly argues, this approach no longer makes much sense. It assumes that deterrence will fail in two places where our commitments are now unambiguous and our forward-deployed capabilities considerable. It downplays the facts that Iraq remains only 50 percent as strong as a decade ago, that North Korea's gross domestic product has declined by half since 1990 and that South Korea has a robust and increasingly modern military.
It also fails to recognize major improvements in U.S. forces that have occurred since Desert Storm in the areas of precision strike and strategic mobility.
If today's two-war framework is excessive in some ways, it pays insufficient heed to other challenges. Taiwan could require assistance to break a Chinese naval blockade designed to coerce the island into accepting a conditional surrender. Or Pakistan's government might ask for help if the country started to collapse and it worried about losing its nuclear weapons to extremist factions.
For all the hypothetical military operations that do seem plausible, many more do not. The United States may be prepared to fight China to defend Taiwan, but it will not fight China to liberate Tibet or fight Russia to protect human rights in Chechnya.
It may contribute to a peace operation in South Asia or the Middle East or Indonesia, but it will not seek to conquer land there or anywhere else. It has no need to worry about again fighting its former World War II adversaries. To put it differently, land wars in Eurasia against large powers are thankfully not in the cards.
The bottom line is that the United States still needs the capacity for a single, all-out war resembling Desert Storm together with a smaller combat operation elsewhere. Allowing for the possibility of a small peacekeeping mission as well, the U.S. military needs to remain 90 to 95 percent of its current size.
That may frustrate those anxious to cut combat forces in order to fund a military transformation for the wars of the future. But deterring those wars is just as important as preparing to fight them. And deterrence continues to require some form of a two-war capability.