Iron Key has a USB key for “enterprise and military” applications. Enterprise, because it is using hardware encryption and military because it’s rugged, thanks to its shock and water resistant casing. From the website:
“A password is used to unlock your IronKey, and this is verified in hardware. If an IronKey is lost or stolen, attempts to unlock or tamper with the IronKey will trigger a self-destruct sequence, ensuring data is kept confidential.”
And I guess that in a life-or-death situation, throwing the key to the adversary’s face could even save your life.