The cocaine trade between Mexico and the U.S.

“‘They erect this fence,’ he said, ‘only to go out there a few days
later and discover that these guys have a catapult, and they’re flinging
hundred-pound bales of marijuana over to the other side.’ ┬áHe paused and
looked at me for a second. ‘A catapult,’ he repeated. ‘We’ve got the
best fence money can buy, and they counter us with a 2,500-year-old

Read more about the story at The NY Times

CRYPTO-GRAM by Bruce Schneier (personal communication, July 15, 2012)