Bizarre statement from our president

I gotta say, my reaction to this was “Whuuh?” At the opening of the Clinton Library:

Bush appeared distracted, and glanced repeatedly at his watch. When he stopped to gaze at the river, where secret service agents were stationed in boats, the guide said: "Usually, you might see some bass fishermen out there." Bush replied: "A submarine could take this place out."

What the #$@%?!?!?! What is with this guy? This is not a military man's mature, considered assessment. This is the assessment of a teenager with a smattering of military knowledge. It strikes me more as the paranoid delusions of raging drunkard than the careful, measured estimates of a responsible adult. How in the heck is a submarine supposed to get all the way up the Mississippi, a journey of about 700 to 800 miles along one of the most heavily-traveled rivers in the world? If one looks at a Mississippi Riverboat, one might notice something interesting about the hull, it's flat!! Why would that be? Perhaps because there are a great many sections where the river is shallow, where a boat with a deep draught can't go. The Wikipedia makes it clear that the river has undergone extensive renovations streching back to the early 1800s and that there is a mandate to keep a nine-foot-deep channel open for commercial traffic. Yes, that means that for a grown man to expect a submarine to travel up the Mississippi to take out a library would indeed, be completely insane.