You can fly wherever you want. No international commercial airline will let you on their plane unless you have a valid passport / VISA for the destination. If you show up by private plane, you will have to show your passport to enter the country, or else you are denied entry.<p>Currently, Snowden is denied entry to Russia, and is stuck in the "Transportation Zone" of a Russian airport, unable to enter the country. Snowden was in discussions for asylum with Russia (who would issue papers allowing him in if granted), but Snowden has reconsidered this option and is seeking asylum elsewhere.
A better question is if such a flight would ever arrive considering how close it would come to the US east coast.<p>Remember it's now magically legal to kill US citizens without a trial.<p>What makes me ill is that there would be a number of people arguing on both conservative and liberal networks that this is acceptable.