Now that the second of two counterinsurgency wars, Afghanistan, seems on the road to de-escalationmainly out of flagging American public support for the quagmireit is a good time to ask what type of military the United States should have in the future. Although the U.S. Army has borne the brunt of the fighting in Afghanistan and Iraq and has equipment that has been heavily used and beat up from years of fighting, the Obama administrations new military strategy is now downplaying the chance of another major land war and focusing on air and sea power.

Surprisingly, this is a good idea, but the administrations thinking needs to be significantly modified. The administrationdespite yawning budget deficits of its predecessors and its own making, which continue to add trillions to the already humongous national debt that is now north of $15 trillionhas developed the military strategy of a declining empire. The strategys emphasis on air and sea power unfortunately continues the global projection of American power.

Yet both the abysmal budget outlook and the U.S. Constitution require a dramatic departure from current U.S. globe-girdling ambitions. America can no longer afford this world empire, which has always been unconstitutional. The Constitution clearly states that the government, particularly Congress, should provide for the common defense. The nations founders would have violently disagreed with then-President George W. Bushs slogan that the best defense is a good offense. At the Constitutional Convention in 1787, the founders, based on bad experiences with 18th-century European monarchs, were most skittish about a strong executive using a standing army to involve the country in foreign wars of intrigue; they knew that the cost of those wars, both in blood and treasure, fell to the common citizen. Since World War II, however, the founders version of military restraint has been pushed out in favor of an imperial president ignoring the constitutional war power of Congress and getting the country into many imperial dustups overseas.

Economic and budgetary problems and the tar pits of Afghanistan and Iraq have soured the American foreign policy elite on conducting expensive land wars, but the rise of China has allowed the Navy and Air Force, bit players in the two latest counterinsurgency conflicts, to successfully renew pressure for global projection of sea and air power.

Because the United States may have the best intrinsic security of any great power in world historywith two great ocean moats, weak neighbors, and nuclear weaponsit is wise to give more emphasis to air and sea forces than to ground forces. But configuring those forces for offensive power projection is costly and unnecessary.

The active Army and even the Marine Corps should be significantly reduced, with some of the cut forces transferred to the cheaper National Guard and Reserves, which can be kept at a high state of readiness for activation in a dire national emergency. Also, this transfer would help better integrate the volunteer Army with the nations citizenry while avoiding conscription.

The Navy and Air Force need to be reconfigured to a cheaper defensive posture. The number of Air Force tactical fighter wings can be significantly reduced, because most of the worlds air forces are far less capable than Americas and cannot project power to reach U.S. shores. In addition, cheaper unmanned drones could replace some manned aircraft.

The number of Navy aircraft carrier battle groups needs to be drastically reduced and the Navy reconfigured to emphasize submarines. Navy carrier-based planes provide much less air power than Air Force aircraft during an all-out war with a great power because they must carry lighter payloads due to the short runways on the flat tops. Carriers are mainly for show-of-force power projection and specialized warfare when land bases are not available. One might think that carriers would be more valuable now, given Obamas shift of emphasis to the Pacific theater, but their vulnerability, and the near certainty that other countries will make land bases available for the American Air Force during any big war against China, makes them of dubious value. Recent history has shown that the submarine is probably the most potent weapon at sea, but it is mainly used to deny the enemy access to the waters rather than to control them. Also, the troubled littoral combat ship, a small vessel to be used to project power off enemy coastlines, should be scrapped because of the shift to a more defensive strategy and because its poor defenses require operation only with larger ships.

Most future Army weapon systems have already been cancelled because of cost overruns, poor performance, production delays, or budgetary infeasibility. But thats less of a problem if the Army is used only for defensive purposes; existing M-1 tanks, Bradley fighting vehicles, Apache and Kiowa helicopters, and Humvees can be cheaply upgraded with new sensors and weapons. In fact, given the rapidly changing world of electronics, which are so important on the modern battlefield, the forces of all services can get more rapid updates by modifying old platforms with new sensors and weapons than by waiting a decade or more for new platforms with then-outdated electronics.

A recent study showed that the United States could hit all the targets needed to devastate a great power opponent with only a few hundred atomic warheads. The United States should unilaterally move toward a minimal deterrent nuclear force. The costly and ineffective missile-defense programs should be scrapped.

Finally, cutting Air Force air wings, Navy carrier battle groups, and Army and Marine divisions and brigades would allow a significant reduction in personnel, the most expensive part of the military.

Thus, a much leaner, defensively oriented military could better safeguard the nations security during a time of economic and fiscal crisis, especially if the looming budget sequestration at the beginning of 2013 actually occurs. During the national fiscal calamity, everyone and every institution must make sacrifices; the military is no exception.