Former intelligence agency contractor Edward Snowden (C) and Sarah Harrison (L) of WikiLeaks speak to human rights representatives in Moscow's Sheremetyevo airport (REUTERS/Human Rights Watch/Handout)

NSA leaker Edward Snowden has been granted temporary asylum in Russia and has reportedly left Moscow's Sheremetyevo Airport, his home for five long weeks. But there's a catch for the U.S. fugitive. Well, this being Russia, probably several catches, but one of them is that his asylum will last for only one year. The Russian transit papers he was given are clearly marked as expiring on July 31, 2014.

Given that it took Snowden this long just to get out of the airport, he might reasonably be concerned about whether 12 months will give him enough time to either flee to another country or secure a more permanent status in Russia. Under Russian law, as ably explained by Radio Free Europe's Tom Balmforth last week, Snowden has three potential paths to shelter in Russia, only one of which offers permanent asylum. The other two are temporary. Barring some high-level political intervention – which is surely possibly, though hardly guaranteed given Russian President Vladimir Putin's past comments on the matter – none of Snowden's options looks especially promising.

Here's a quick rundown of the various paths open to him:

1. Political asylum (permanent)

This is the only path to permanent shelter in Russia. Russian law on political asylum sounds like most other countries' laws: It grants "asylum or protection from persecution or a real threat of becoming a victim of persecution" for people facing ill-treatment in their home countries for "social-political activities or convictions that do not contradict the democratic principles recognized by the international community and norms of international law."

Sounds straightforward, but Radio Free Europe found only 14 people in the past five years who had applied for political asylum in Russia -- and none of them appeared to have been successful. That may be in large part because winning political asylum requires a presidential decree.

2. Refugee status (temporary)

Russian law says foreigners on Russian soil can apply for refugee status if they fear they could become a "victim of persecution due to their race, religion, citizenship, nationality, membership in a particular social group or political belief." Refugees in Russia tend to come from some rough spots: Syria, Afghanistan and Central Asia are among the biggest sources. (So is more peaceful and stable Georgia.)

But refugee status only lasts for up to three years and is reviewed every year. It's not clear whether it can be renewed at the end of the three years.

It's also rarely granted. Radio Free Europe examined official Russian government statistics and found that, between January 2007 and April 2012, 12,500 people applied for refugee status but only 961 got it – a success rate of just 7 percent. That's down significantly from earlier years, when the rate was around one-in-three. Immigration from Central Asia is a sensitive issue in Russia, where ethnic Russian birth rates are declining rapidly as legal and illegal immigration from post-Soviet Central Asian states rises.

3. Extension of 'temporary asylum' through legal appeals (temporary)

Snowden's temporary-asylum status may run out in one year, but that doesn't mean Russia will automatically deport him on Aug. 1, 2014, if he's been denied permanent political asylum. As in the United States, he can continue living in Russia if he is in the process of appealing that decision. He could appeal, first, directly to the federal immigration service and then to a Russian court. The process typically lasts about a year, which means that his one-year temporary asylum could functionally last two years if he times his appeals well.

Caveat: Snowden's case is far from typical

The Russian refugee and asylum processes are daunting, but they're normally braved by regular families or individuals from places such as Syria or Afghanistan – not by high-profile and geopolitically significant American intelligence contractors. Putin has clearly taken an interest in the case and has publicly stated that Snowden can stay as long as he stops releasing information "damaging to our American partners."

Still, temporary asylum is much easier to get in Russia than are other forms of shelter. Between 2001 and 2007, according to government statistics, 43 percent of applicants were granted the one-year reprieve.