Because those were the odds estimated by one of Obama's top national-security advisors -- who nevertheless advocated a drone strike instead of a Special Forces mission.
Nearly everyone in the United States agrees that our government was justified in hunting and killing Osama bin Laden, a confessed and unrepentant mass murderer who escaped justice for years after masterminding the most devastating terrorist attack in American history, boasting about it, and promising more of the same. The operation that killed him is the subject of Mark Bowden's book The Finish, a lengthy magazine article by the same author, and several related interviews. So far, reactions to his account have focused on whether the team of Navy Seals who penetrated Bin Laden's compound were justified in shooting him, or ought to have captured him alive. It's an interesting legal and moral question, but hardly the only one raised by Bowden's reporting.
Consider the moments a bit earlier in the chronology, before the Special Forces team was dispatched. Team Obama had intelligence suggesting that Bin Laden might be the tall man they'd spotted walking around the garden in a walled compound. What were the odds that it was him? The national security team gave answers ranging from a 30 percent chance to a 95 percent chance. Most fell somewhere in the middle. Obama finally directed that they should make their decision as if there was a 50 percent chance that the man inside the compound with two other families and numerous children was Bin Laden. Should they blow the whole thing up? Try to hit the man with a small missile that would kill only him, but might miss its target? Do nothing? Or send a team to gain entry into the compound to see who and what was inside?
We know the outcome.
The raid was ordered. Bin Laden was there. The Special Forces team killed him, along with his courier, Ibrahim Saeed Ahmed, the courier's brother and his wife, and Bin Laden's 23-year-old son.
The team mostly shot the men on sight, and spared women and children whenever possible. But what about the plans that were considered but not taken? They afford a rare opportunity to examine actions that high-level national security figures actually recommended to the president.
Is the national security establishment bound by the moral norms we'd hope?
The record is mixed.
The option to reduce the entire compound to rubble, along with neighboring houses that would be inadvertently but inevitably destroyed, was immediately rejected by Admiral Bill McRaven and President Obama, who knew among other things that it would definitely kill many innocent children.
On the other hand, Mike Leiter, director of the National Counterterrorism Center, took a position that strikes me as alarming. In his judgment, the odds that the mystery man in the compound was Bin Laden was around 40 percent -- more likely than not, he thought, it wasn't him.
Yet according to Bowden's account, he nevertheless advocated a drone strike to kill the man! "It startled me, to be honest, that some people who assessed the likelihood of it being bin Laden there as less than 50 percent nevertheless advocated launching a missile," Bowden said in a followup interview. It would be nice to know if national security officials apply this same standard to drone strikes in Pakistan, Yemen, and elsewhere, but Obama won't tell us their criteria.