By Larry Kudlow - May 5, 2011

In the aftermath of the killing of Osama bin Laden, I found myself agreeing with Charles Krauthammer that this was a global game-changer for American greatness. It was a gutsy and courageous decision by President Obama, brilliantly executed by the Navy SEALs and all the intelligence and support behind them.

As Krauthammer put it, after the tough slogs in Iraq and Afghanistan, this amounts to the restoration of unquestioned U.S. military dominance. America has not slipped, nor has our military reach and power.

But now I want to ask a more difficult question. With the killing of Osama, is the Afghan mission complete? The original post-9/11 goal was to kill bin Laden and wipe out al-Qaida. Now that we've killed bin Laden and dismantled so much of al-Qaida, do we really need to trudge through an even longer war in Afghanistan?

Ayman Al-Zawahiri is in Pakistan. Perhaps the SEALs can dismantle him. Anwar Al-Awlaki is in Yemen, and perhaps al-Qaida can be dismantled there. But regarding the broader war in Afghanistan, I was taken by a quote from Rep. Peter King on National Review Online. He said, "The enemy is now more of a threat from within than it is from overseas."

I am no military or foreign-policy expert. But I do know the cost of supporting a corrupt regime like Hamid Karzai's in terms of blood and treasure. The cost is steep. I speak here as a hawk, not a dove.

In dollar terms, the cost of the Afghan war is roughly $450 billion today, and according to Congressional Budget Office projections, it is scheduled to rise by perhaps another $500 billion.

Meanwhile, the Congressional Research Service reports that we have doubled our average troop strength in Afghanistan from 44,000 to 84,000 as part of the surge. Troop strength there is expected to average 102,000 in FY2011. A slight 4,000 troop decline is projected for FY2012, but the longer-term commitment continues to the end of 2014.

Thus far, nearly 1,600 U.S. troops have been killed in action in Afghanistan. To me, this is the most tragic part. Of course, I wholeheartedly support our troops. But is this blood really necessary? Are the projected future costs really necessary?

Again, I ask myself: All this to support Karzai? Isn't this the sort of nation-building that the late William F. Buckley Jr. opposed? Are American national-security interests really tied up in Afghanistan? Is now not the time to contemplate a much more rapid troop withdrawal from Afghanistan?

I am willing to concede that the U.S. needs to fight the expected Taliban spring surge. But after that, is it worth it to stay any longer? And does our mission really include wiping out the Taliban in Afghanistan, a seemingly impossible task?

Going forward, what exactly is our real mission in Afghanistan? That's the basis of my concern. Are we as Americans and conservatives really convinced that the continued mission is worth the lost blood and treasure? Is now not the time to leave?

What exactly are we doing in Afghanistan? And how do we get out of it?