Letterman, who often pretends to be a clueless goof when it comes to serious topics, actually is politically astute. And he hit on one of Hagel's chief appeals as Barack Obama's nominee to become secretary of defense: Hagel doesn't believe in needless wars or endless wars or wars as our first choice.
And, in that, both he and the president match the public mood perfectly.
Iraq has been a calamity, pouring precious U.S. lives (to say nothing of innocent Iraqi lives) and dollars into a war over mythical weapons of mass destruction. Does anybody still doubt that George W. Bush wanted to believe in those weapons because he wanted to finish off the dictator that his father had failed to remove?
I am no fan of homicidal dictators like Saddam Hussein, but the world has other homicidal dictators, and before we decide to wage nearly nine-year, trillion-dollar wars to remove them all, maybe we ought to have a better reason than unresolved father-son relationships.
Our invasion of Afghanistan was certainly justified, but we are still fighting there long after our legitimate objective has been accomplished: the crippling of al-Qaida's ability to strike at the American homeland and the destruction of al-Qaida's top leadership.
But we have remained in Afghanistan to build it into an American suburb, where everybody will think like we do about human and civil rights. It is a worthy but dream-like goal, and all we have really accomplished is to prop up a corrupt and unpopular regime in Kabul.
If that echoes Vietnam to you, it should. Hagel was a sergeant in Vietnam, a squad leader in the 9th Infantry Division, where he was awarded two Purple Hearts. He, like Obama's nominee for secretary of state, John Kerry, learned some valuable lessons over there:
Be careful about feeding the meat grinder. The butcher's bill is always going to be higher than you think. And the members of Congress who bravely vote to fund our wars don't have to fight in them.
Here is Hagel in an interview last year with Robert Nolan, an editor at the Foreign Policy Association:
"One of the reasons we're in trouble in Afghanistan is because we went well beyond our mission. We accomplished the mission, then we took our eye off the ball and intervened, invaded and occupied Iraq. And now, 12 years later, we're not sure what our mission is. ... We always learn. They're tough lessons to learn. Vietnam was a tough lesson for us to learn."
Even though Hagel is a Republican, some Republican hawks read those words and shudder.
How can we have a defense secretary who does not want more and more money to invade more and more nations, but believes the money would be better spent on cybersecurity at home?
And how can we have a defense secretary who actually says America is capable of making mistakes and that we should learn from them?
How? Easy. We put Hagel in the job. As a senator, did he vote against gay rights and make ugly comments about homosexuals? Yes. He has apologized and now says he is a full supporter of Obama's position on gay rights and gays serving in the military.
Did he once use the term "Jewish lobby" instead of "pro-Israel lobby"? Yes, in 2006, he said: "The political reality is that the Jewish lobby intimidates a lot of people up here. I have always argued against some of the dumb things they do because I don't think it's in the interest of Israel. I just don't think it's smart for Israel."
As someone who has zero tolerance for anti-Semitism, I don't think Hagel is an anti-Semite, and urging Israel to follow policies that are in both its and our best interests is hardly misconduct.
There is one other quality a good defense secretary should have.
"We lead the world; we don't dictate to the world, we don't impose to the world, we don't intervene everywhere, and we don't occupy and invade," Hagel told Robert Nolan last year.
"We work with our allies. We do exactly what Eisenhower, Truman and Marshall, and all those other wise leaders after WWII did. That's what's brought us over the last 65 years to where we are."
Chuck Hagel is a man who loves his country more than he loves war. And that is exactly the kind of man we need as our secretary of defense.
(Daily Corinthian columnist Roger Simon is chief political columnist of politico.com, an award-winning journalist and a New York Times best selling author.)