ANOTHER AL QAEDA NO. 3…. Stop me if you’ve heard this one: al Qaeda’s #3 man has been killed.

A senior al Qaeda terrorist who allegedly plotted and carried out attacks against U.S. and coalition forces was killed in Pakistan, a knowledgeable Western official and a military source told CNN Thursday.

He was identified as Abu Laith al-Libi, 41, who was on the military’s most wanted list.

Al-Libi was thought to have been involved in the February 2007 bombing at Bagram Air Base in Afghanistan while Vice President Dick Cheney was visiting.

The knowledgeable Western official said al-Libi was “not far below the importance of the top two al Qaeda leaders” — Osama bin Laden and Ayman al-Zawahiri.

CNN Middle East analyst Octavia Nasr called al-Libi the third-ranking terrorist in al Qaeda and fourth in the world.

This is certainly welcome news. I’m curious, though, if anyone has a list of al Qaeda #3s who’ve been captured or killed recently. I was keeping a list for a while, and I think al-Libi is the seventh, following Hamza Rabia, Abu Faraj al-Libbi, Saif al-Adel, Khalid Sheikh Mohammed, Mohammed Sheikh Mohammed, and a senior operational leader identified in court documents as “C-2.”

You’d think, after a while, al Qaeda’s #4 guys would stop seeking promotions.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.