Who can threaten us on our soil? I'd love to know.
I don't mean someone blowing up a shopping mall in the name of Allah. I mean what foreign nation threatens our sovereignty?
I think "who would want to" would be the better question to ask?..
Then you would have to narrow it down to those who have the capabilities to do such...
Of course you would have to look at the economic validity to do such.
I suppose China would love to attack us, however they have too much at steak, Russia as well... Those are the two major nations that would attack us...
They'd both love our resources, however they know they would have to destroy them to gain access to our country, hence making an invasion moot. Not to mention the global economic ramifications that would hurt them..
North Korea would love to attack us but they don't have the resources to do such.
Iran however is crazy enough and has enough resources and capabilities to attack us. Ahmadinejad would certainly go on some Middle East conquest if Paul stuck to his no intervention policy.... Ahmadinejad would build a coalition of Islamic countries/states and before you knew it you would have an army the size of China's army heading for the shores of the US looking to do what the Spanish did in South America circa 16th century..