The disclosure of Gen. Stanley McChrystal's assessment of our strategy in Afghanistan has generated a healthy discussion about whether we should remain there, what our mission should be, whether the benefits to our national security are worth the anticipated cost, and whether we can actually come up with the resources required. It is unfortunate that his report has been wrongly characterized as a call for more troops. Rather, McChrystal is offering a new strategy. "Without a new strategy," he says, "the mission should not be resourced."

McChrystal's strategic assessment is unassailable, but it is important to point out what his report does not address and what the president, the national security apparatus, and the Congress would do well to consider.

General McChrystal was not asked to examine the fundamental rationale for our military involvement. For him, it was a given. McChrystal restates the existing casus belli, saying that "if the Afghan government falls to the Taliban — or has insufficient capability to counter transnational terrorists — Afghanistan could again become a base for terrorism, with obvious implications for regional stability." That is a true statement, but it does not automatically follow that the U.S. should maintain a massive civil-military campaign to prevent the fall of the Afghan government.

A real mission statement for a military force should sound like this one given to General Dwight Eisenhower in 1944: "You will invade the continent of Europe and destroy the Nazi war machine." This isn't General McChrystal's fault. However, McChrystal can't resist an attempt to redefine his nebulous mission statement, saying that "accomplishing this mission requires defeating the insurgency." He is absolutely right that if the U.S. and our Afghan allies are going accomplish all of the things in the official mission statement, we must defeat the insurgency. Perhaps our national security really doesn't require us to accomplish all those things, however.

How much more secure is the United States because bin Laden is denied a base in Afghanistan, when he is operating in Yemen, Somalia, and Pakistan?

Al-Qaida is our principal security challenge, and we should apply our military resources to crippling or destroying it wherever it can be found. If nation-building is (1) achievable, (2) within our means, (3) will destroy al-Qaida, and (4) is cost effective, then we should undertake it. If nation building doesn't meet those tests, then that should not be our approach. There are other options for dealing with al-Qaida, including airpower, commando-style raids, and other special intelligence operations which are far less costly than attempting to revive a failed nation state.

The fall of the Afghan government to a resurgent Taliban certainly has implications for its neighbor, Pakistan. We should be concerned that Pakistan, a nuclear power, could soon join the ranks of failed states run by radical Islamists, and a Taliban success in Afghanistan might push it over the edge.

However, it may not be necessary to preserve the Afghan government against a Taliban insurgency in order to prevent Pakistani nuclear weapons from falling into the hands of radical Islamists.

Even if a campaign to defeat the Afghan insurgency is the best answer, what will it cost? McChrystal hasn't addressed this question yet, except to say that it will cost more. Another brigade or two is manageable. Another 15 or 20 is not, unless the United States is willing to undertake some truly extreme measures. McChrystal correctly notes that resources alone will not guarantee the success of his new strategy. That's why a responsible commander-in-chief will carefully reassess before investing more blood and treasure.

Honolulu attorney Thomas D. Farrell served as an Army Reserve intelligence officer during a 30-year career, including a tour in Iraq from June 2005 to May 2006. He wrote this commentary for The Advertiser.