No nation can dream of challenging us in the air or at sea. We have a huge nuclear arsenal capable of inflicting mass annihilation on a moment's notice.

Meanwhile, the demands on our military are easing rather than growing. Under the agreement Bush signed with the Iraqi government, which Obama has reaffirmed, we are supposed to be out of Iraq by the end of 2011. The threat from al-Qaida has been greatly reduced.

Still, looming threats can always be found. The Washington Post had a story the other day about China's military expansion, which has enlarged its budget to more than $100 billion in 2008. This trend worries the Pentagon. "Given the apparent absence of direct threats from other nations," says the Post, "the purposes to which China's current and future military power will be applied remain uncertain."

But our spending that year was more than $600 billion. And China, come to think of it, is not the only country spending a lot on the military despite the absence of direct threats from other nations.

Benjamin Friedman of the libertarian Cato Institute in Washington notes something generally overlooked in Washington: "In a literal sense, the United States does not have a defense budget." Our military outlays go for all sorts of purposes -- "the purported extension of freedom, the maintenance of hegemony, and the ability to threaten any other nation with conquest." But defending the nation's basic security? That's a small share of our military outlays.

If we focused on what is vital for our safety and independence, we could spend a lot less money. But if there is no limit to what we have to do to police and remake the world, there is also no limit to what we can spend.