google [army keycard] -- about 64,600 results
http://www.google.com/search?hl=en&q=army keycard&btnG=Searc...

"A keycard is a small credit card-sized device that opens doors. Sometimes a keycard uses a magnetic strip (like a credit card) or a barcode, but most often use RFID (radio frequency identification).

"For the paranoid, keycards are convenient because it means that they can keep track of who opened what door when (because every keycard transmits a different ID -- it's like everyone has a different key, but they all open the same lock.) Another advantage of keycards is that revoking access is a simple matter of telling the computer not to allow certain ID's through."
http://www.everything2.com/index.pl?node_id=677334&

This sounds like something the Army would use.