As the multitudes arrive for the historic inauguration of Barack Obama, the most high-tech security bubble ever created is in place to protect

the incoming president from any foreseeable act of God, nature or man.

But authorities say they still dread the “X factor” - intangibles that they cannot control and that could upend their most carefully laid plans by panicking the immense crowd. At the top of that list, they say, is the lone-wolf individual or small group capable of slipping through the intelligence and security net. A burst of gunfire or an explosion, they know, could cause significant casualties or pandemonium.

That is considered extremely unlikely. Law enforcement and intelligence officials say they have seen nothing to suggest the president-elect or his inauguration are being targeted.

[ Via LATimes ]