Beware the open mike.

Gen. David Petraeus, the top commander in Afghanistan, learned that lesson yesterday in greeting Defense Secretary Robert Gates on a visit to Kabul.

Nearby microphones picked up Petraeus joshing to Gates: "Flying a little bigger plane than normal -- you gonna launch some attacks on Libya or something?"

"Yeah, exactly," Gates responded, chuckling.

Oh, well. A little war zone humor, we suppose.