How serious do we take national defense? In this same area is the first TVA dam that was build about 15 miles upstream from Oak Ridge. While the Manhattan Project was going on during WW2 the dam had gun placements below it. There was concern that a rouge plane from Japan or Germany, or possibly a stolen plane would work it's way up the Missippi & Tennessee River and take it out. Oak Ridge was a secure city and the old guard stations still stand today in some places. The Air Force up till I think the late 1960's operated a radar base north of Oak Ridge.
We need to rethink our International Water Boundry and set it to at least 15 miles out with a Coast Guard beefed up to enforce it.
Luckily, the threat remained just that. But the idea sounds chillingly familiar to the events of 11 September, when hijackers used three fuel-laden jetliners to attack and destroy New York's twin towers and part of the Pentagon, near Washington.
One nuclear expert, in fact, suggests that the fourth plane hijacked on 11 September may have been bound for a nuclear facility.