Flee to an Embassy
If a government will take him, Snowden could try to make a mad dash to an embassy in Moscow. Embassies have become modern-day sanctuaries for many asylum-seekers because of their legal inviolability -- it's what has protected people as diverse as Chen Guangcheng, Sam LaHood, and Julian Assange. Getting there, though, is a problem. It's 20 miles from Sheremetyevo Airport to the Venezuelan embassy in Moscow, and a couple miles farther to the Bolivian embassy. And while a diplomatic vehicle sent by an embassy can't be searched legally, it can still be stopped. (The BBC pointed out this problem when Assange took refuge in the Ecuadorean embassy last year.)
Even if Snowden gets to an embassy, that may not be enough to apply for asylum. Contrary to popular belief, embassies are not technically foreign soil. As my colleagues Uri Friedman and Joshua Keating noted last year, "What this means in practice is that once someone seeks refuge in an embassy, the foreign government often enters into negotiations with the host government about the fugitive's fate." Snowden could hole up in an embassy, as many have done before him, but he'd be in more or less the same predicament as he's in at the airport terminal.
Get 'Diplomatic Asylum'
Without traveling to a specific country and applying for asylum from within that country's formal territory, Snowden could be granted "diplomatic asylum." Ecuador conferred this status on Julian Assange in August 2012 to try to shelter him from extradition. The problem? The United States doesn't recognize diplomatic asylum.
"The United States is not a party to the 1954 OAS Convention on Diplomatic Asylum and does not recognize the concept of diplomatic asylum as a matter of international law," the office of then-State Department spokesperson Victoria Nuland said in a statement after Ecuador granted the WikiLeaks founder asylum. The United States, for its part, only grants asylum to people in the country, in accordance with the Refugee Act of 1980, and has been cautious to avoid labeling instances in which it has protected political dissidents abroad as asylum.
Hitch a Ride on a Foreign Leader's Plane
Snowden would have a hard time getting to Venezuela, but what if Venezuela came to him? Venezuelan President Nicolás Maduro was in Moscow for an energy conference this week -- could he just spirit Snowden away with him? Possibly. Maduro has been vague about whether he'd consider plucking Snowden from Sheremetyevo Airport. He told RT on Tuesday that he has not yet received Snowden's request for asylum; when asked at a press conference if Snowden would be coming back with him to Caracas, he reportedly laughed. "What I think I will take are many accords that we are going to sign with Russia and lots of Russian investments in petroleum and gas," Maduro said. "That is what we are going to take to Venezuela." But the Venezuelan leader also downplayed the importance of Snowden's location. "We should not think about how Snowden would escape Moscow airport but to analyze what information this young person provided," he told RT. "If in the next days this person leaves the airport by plane or by boat or however, this is not so important" (Sheremetyevo is landlocked, so a boat is probably out of the question).
If Bolivian officials are to be believed, Portugal, France, and Italy took this scenario seriously enough that they refused to permit Evo Morales's plane from entering their airspace on Tuesday -- out of concern that Snowden was on board. The Bolivian president was returning from the same conference that brought Maduro to Moscow.
Of course, Snowden's biggest stumbling block in each of these scenarios is Russia's enforcement of international law. And in Russia, there's no guarantee that those laws will be enforced. If Vladimir Putin decides Snowden should be someplace other than Sheremetyevo, chances are, he will be.