Here's a CENTCOM General in a recent interview:

"The Internet is the most important venue for the radicalization of Islamic youth."

"I see 16-, 17-year-olds who have been indoctrinated on the Internet turn up on the battlefield. We capture them; we kill them every day in Iraq, in Afghanistan."

"It's a battle of perceptions, and al Qaeda understands it. And America needs to understand it."

Maybe, if we got the American schoolchildren to write their letters to Iraqi, Iranian, Saudi, Syrian children ... or, they could make videos to them, and post them on YouTube.

Update: Juba the Sniper is all the evidence you need.