On June 18, 2001, then-Secretary of Defense Donald Rumsfeld sent out a brief memo quoting a former US Lt. General warning his troops that they may be in harms way.

Rumsfeld's memo, titled "Chesty Puller" -- the nickname of Lt. Gen. Lewis Puller, a veteran of World War II and the Korean War -- read in full:

General Chesty Puller once said to his troops:

"The enemy is ahead, the enemy is to the right, to the left, behind, and above.

They won't get away this time."

It's unclear who Rumsfeld's now-declassified memo was sent to, but five days later, CNN ran an item headlined, "U.S. troops on alert for possible strike by bin Laden followers." The article quoted anonymous sources affirming that U.S. troops in the Middle East were on "high alert" following a "nonspecific but credible threat" from Osama bin Laden.

The memo was posted to Rumsfeld's website on Tuesday.